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Full text of "Analysis of the durational aspects of connected speech with reference to stuttering"

AN ANALYSIS OF THE DURATIONAL 

ASPECTS OF CONNECTED SPEECH 

WITH REFERENCE TO STUTTERING 



By 
BRUCE C. FLANAGAN 



A DISSERTATION PRESENTED TO THE GRADUATE COUNCIL 

THE UNIVERSITY OF FLORIDA 

IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE 

DEGREE OF DOCTOR OF PHILOSOPHY 



UNIVERSITY OF FLORIDA 

June, 1966 



ACKEO\^JLEDGMENTS 

Tlie author wishes to express his gratitude to Doctor 
McKenzie W. Buck for his continuing interest and encourage- 
ment throughout their academic association. Grateful 
acknov/ledgment is expressed to Doctors G. Paul Modre and E. 
Porter Home for their guidance during the author's doctoral 
program and preparation of this dissertation. Sincere 
appreciation is expressed to Doctor Wilse B. V/ehh for his 
salient and stimulating contributions to the author's 

doctoral program. 

Special acknowledgment is given to Doctors Thomas B. 
Ahhott and Kenneth R. Bzoch for their cooperation in making 
subjects and facilities available for obtaining data. Doctor 
Leslie P. Malpass and Dean Edwin P. Martin of the University 
of South Florida are especially acknowledged for their con- 
tinuing support and for the utilization of facilities to 
collect the data for the major portion of this dissertation. 

The Operational Applications Laboratory, Air Force 
Cambridge Research Center is acknowledged for funding the 
collection of the data for the preliminary research; Con- 
tract No. AP19(60^)-6127, Israel Goldiamond, Principal 
Investigator, 



IX 



TABLE OF CONTENTS 



ACKNOWLEDGMENTS 
LIST OE TABLES 
LIST OE EIGUEES 
Ciiapter 
I. 



II. 



INTRODUCTION 

Review of the Literature 

METHOD 

Selection, of Subjects 

Apparatus 

Recording Procedures 

Oral Reading; Time and Disfluency Measures 



Page 
ii 
iv 

vii 



1 

4 



III. 



15 

16 

17 
20 

22 

PJiSULTS 2^ 

Reliability of Individual and Group Measures 24 
Comparis on"of Eluent and Disfluent Speech. 
SaniDles 



lY. 



Effects of Time of Say and Experimenter- 
Sub rject Combinations 

DISCUSSION 

Implications for Application and Eurther 
Research 



V. SUMMARY 
APPENDICES 
A. 



PRELIMINARY RESEARCH: DURATIONAL PROPERTIES 
OE SILENCE INTERVALS DURING ORAL READING 



B. SUPPLEMENTARY STATISTICAL SUMMARIES 

C. Z SCORE DATA FOR THE INDIVIDUAL STUTTERING 

SPEAICERS 

REFERENCES 
BIOGRAPHICiJ; SKS'TCH 



30 
34 
36 
41 

45 
48 

49 
80 

91 
104 
108 



111 



LIST OP TABLES 
Table Page 

1. Means, standard deviations and correlations of 
Trials I and II for frequency of speecli events 

of 54 fluent speakers 26 

2. Means, standard deviations and correlations of 
Trials I and II for frequency of silence events 

of 64 fluent speakers 29 

3. Means, standard deviations and t tests 
comparing 12 stutterers with 16 fluent speakers 

for frequency of speecli events 32 

4. Means, standard deviations and t tests 
comparing 12 stutterers with 16 fluent speakers 

for frequency of silence events 33 

5. Number of silence intervals recorded at each 
duration, when same tape vms run four times . . 56 

6. Oral reading rate for normal subjects 

expressed in words per minute 57 

7. Percent of disfluent words for normal subjects. 60 

8. Oral reading rate for stuttering subjects 
expressed in words per minute 62 

9. Percent of disfluent words for stuttering 
subjects. ..... 64 

10. Eeliability coefficients of the Multiple- 01 ass 

Time Analyzer for speech and silence events . , 81 

11. Reliability of reading time and disfluency 
measurement procedures 82 

12. Summary of analysis of variance for experimen- 
ter-subject combinations by time of day 
variables for reading time of Trial I 83 

13. Summary of analysis of variance for experimen- 
ter-subject combinations by time of day 
variables for reading time of Trial II 83 

iv 



Table 

14. Summary of analysis of variance for 

experimenter-subject combinations by time of 
day variables for disfluencies occurring 
during Trial I . . . . 



Page 



84 



15. Summary of analysis of variance for 

experimenter-subject combinations by time of 



day variables for disfluencies occurrxng 
during Trial II. 



84 



16, Summary of analysis of variance for 
experimenter- subject combinations by time of 
day variables for frequency of silence events 
between 100-149 milliseconds on Trial I. . . . 85 

17, Summary of analysis of variance for 
experimenter- subject combinations by time of 
day variables for frequency of speech events 
between 150-199 milliseconds on Trial I. . . . 85 

18. Summary of analysis of variance for 
experimenter-subject combinations by time of 
day variables for frequency of speech events 
between 400-499 milliseconds on Trial I. . . . 85 

19. Summary of analysis of variance for 
exoerimenter-subject combinations by time of 
day variables for frequency of silence events 
between 450-499 milliseconds on Trial I. . . . 



86 



20. Summary of analysis of variance for 
exuerimenter-subject combinations by time of 
day variables for frequency of silence events 
between 500-549 milliseconds on Trial I. . . . 8? 

21. Summary of analysis of variance for 
exoerimenter-subject combinations by time of 
day variables for the frequency of silence 

events between 600-549 milliseconds on Trial I 8? 

22. Summary of analysis of variance for 
experimenter-subject combinations by time of 
day variables for frequency of speech events 
between 550-599 milliseconds on Trial I. . . . 88 



Table Page 

23. Summary of analysis of variance for 

experimenter-subject; combinations by time of 
day variables for frequency of speech, events 
between 250-299 milliseconds on Trial II . . . 88 

2^, Summary of analysis of variance for 

experimenter-subject combinations by time of 
day variables for frequency of speech events 
between 350-399 milliseconds on Trial II . . . 89 

25, Summary of analysis of variance for 

experimenter-subject combinations by time of 
day variables for frequency of silence events 
between 650-599 milliseconds on Trial II . . . 89 

25. Summary of analysis of variance for 

experimenter-subject combinations by time of 
day variables for frequency of speech events 
between 700-7A-9 milliseconds on Trial II . . . 90 

27. Summary of analysis of variance for 

experimenter-subject combinations by time of 
day variables for frequency of silence events 
beyond 750 milliseconds on Trial II 90 



VI 



LIST OF FIGUESS 
Figure Page 

1. A composite plot of the cumulative frequency 
of silence intervals for five fluent subjects 
reading a 102-4- word passage six times 67 

2. Tlie cumulative frequency of silence events for 
Subject 1 in Trials I, III, and V 70 

3. The ciimulative frequency of silence events for 
Subject 2 on Trials I, III, and V 71 

A-, The cumulative frequency of silence events for 

Subject 3 on Trials I, III, and V 75 

5. The cymulative frequency of silence events for 
Subject ^ on Trials I, III, and 7 7^ 

6. The cumulative frequency of silence events for 
Subject 5 on Trials I, III, and V 75 

7. The cumulative frequency of silence events for 
Subject 6 on Trials I, III, and V. ..... . 77 

8. Z scores at significant speech and silence 

class intervals for male stutterer, age 22 . . 92 

9. Z scores at significant speech and silence 

class intervals for female stutterer, age 18 . 93 

10, Z scores at significant speech and silence 

class intervals for male stutterer, age 25 . • 9^ 

11. Z scores at significant speech and silence 

class intervals for female stutterer, age 18 . 95 

12, Z scores at significant speech and silence . 

class intervals for male stutterer, age 22 . . 96 

13. Z scores for significant speech and silence 

class intervals for male stutterer, age 20 . . 97 

1^, Z scores for significant speech and silence 

class intervals for male stutterer, age 28 . . 98 



vxx 



Pigure Page 

15. Z scores for significant speech and silence 

class intervals for male stutterer, age 19 . • yy 



16. Z scores for significant speech and silence 
class intervals for male stutterer, age 29 - 



100 



17. Z scores for significant speech and silence 

class intervals for male stutterer, age 21 . . 101 

18. Z scores for significant speech and silence 

class intervals for male stutterer, age 2? . . 102 

19. Z scores at significant speech and silence 

class intervals for male stutterer, age 21 . . 10:5 



vxxx 



CHAPTER I 
INTRODUCTION 

Tlie purposes of this research, were to establish 
variance estimates for frequency distributions of speech and 
silence events for fluent speakers during conditions of oral 
reading, to determine the reliability of these dimensions of 
vocal behavior on a test-retest basis, and to assay the 
effects of time of day and experimenter variables on these 
measures. Contingent upon the reliability of the variance 
estimates, a comparison of the frequency distributions was 
made between stutterers and fluent speakers for speech and 

silence events. 

Although the disfluency phenomenon has been an area 
of continuing interest to scientists and clinicians, 
recently, Carroll (196^) indicated surprise at the lack of 
definitive findings concerning disfluency in view of the 
considerable quantity of research devoted to the topic. 
This lack of definitive results is a function of the measure- 
ment procedures employed. Research devised to assess the 
effects of certain independent variables on disfluency have 
relied on human observers to count or rate this phenomenon. 
Reliance on an observer definition of disfluency may be 



considered a special case of psychophysical analysis where 
the properties of the stimuli are unknown. Current psycho- 
physical procedures admit varying degrees of ohserver "bias 
(Goldiamond, 1958) which could obviate the usefulness of 
observer defined procedures for a detailed analysis of dis- 

fluency. 

The information accumulated from previous studies has 
demonstrated some consistent findings relative to the 
properties of disfluency, Disfluent speakers (stutterers) 
as a group have been found to use significantly more time in 
reading a given passage than do fluent speakers (Johnson, 
1961), Also, within stutterers as a group, there has been 
reported a high positive correlation between the judged 
frequency of disfluency and reading time (Sander, 1961). 
From these observations it appears tenable to assume 
observer defined disfluencies occurring during connected 
speech possess correlates which occupy time. 

The problem then arises in discriminating between the 
fluent and disfluent durational characteristics of speech. 
Speech and silence events occurring during connected speech 
can be separated and tabulated by their durations. These 
data may then be assigned to arbitrary class intervals which 
pe3?mit construction of frequency distributions for speech 
and silence events. It was hypothesized: Under specified 
controlled conditions, the frequency distributions of speech 



and silence events will demonstrate reliable mean estimates 
at the selected class intervals. Contingent upon the 
accuracy of this hypothesis, it was further hypothesized: 
The frequency distributions of speech and silence events 
for a group of disfluent speakers will deviate from the 
fluent speakers' means at one or more class intervals. This 
hypothesis was predicated on the cited observation that dis- 
fluent speakers use significantly more time to read a given 
passage. 

In addition to recognizing capricious variability as 
a potential source of limitation, unavoidable variations 
within the controlled experimental conditions would also 
seriously impair the usefulness of these data. Time of day 
and sex of escperimenter in combination with sex of the sub- 
ject are variables within the controlled condition which 
cannot be avoided efficiently. Therefore, two additional 
hypotheses were advanced: (1) The time of day during which 
subjects are run does not significantly effect frequency 
distributions of speech or silence events; (2) The sex of 
the experimenter in combination with sex of the subject 
does not significantly effect frequency distributions of 
speech or silence events. 



Review of the Literature 

Stuttering Literature . Literature pertaining to the 
measurement of disfluency can he hroadly categorized hy 
ohserver defined procedures, or hy correlates of observer 
defined procedures. The disfluency correlates can he cate- 
gorized hy the measurement procedures employed. The 
relevant literature will he reviewed in relation to acous- 
tical, physiological, rate, and durational distrihution 
measurement procedures. Discrimination of disfluent speech 
cannot he separated from the operational procedure used in 
measuring it. To avoid biased assumptions regarding the 
nature of the disfluency phenomenon, the pertaining 
literature will he discussed on an operational level. 

Johnson (1961) reported a procedure, the Iowa Speech 
Disfluency Test, in which tape recordings were obtained 
under several conditions of speaking and oral reading. The 
observer listened to the recordings and categorized judged 
disfluencies into eight types. ■ This test procedure allowed 
as many replayings as necessary to satisfy accurate identifi- 
cation of the disfluencies. The eight categories were (1) 
interjections, (2) part-word repetitions, (5) word repeti- 
tions, (^) phrase repetitions, (5) revisions, (6) incomplete 
phrases, (7) broken words, and (8) prolonged sounds. Rate 
of speaking and oral reading were also computed. These data 
were then compared to norms for normal speakers and for 



stutterers, Saxider (1961) investigated the reliability of 
the Iowa Speech Disfluency Test. The reliability coeffici- 
ents for total disfluencies and speaking rate were 
approximately .90 for a sample of ^0 stutterers and high 
intercorrelations among subtests indicated redundancy. 
Young (1951) reported a similar technique for the evaluation 
of stuttering with the number of categories of disfluency 
types shortened to five for reasons of infrequent occur- 
rence of some categories and confusion among others. These 
categories of disfluency were (1) interjections, (2) part- 
word repetitions, (3) word-phrase repetitions, (^) pro- 
longations, and (5) revisions, Minifie and Cooker (196^) 
suggested a disfluency index considering syllables uttered 
divided by the reading rate for a set passage. Data were 
presented suggesting reliability of this procedure for 
discriminating fluent from disfluent speakers. The tech- 
niques cited involved recording speech samples on tape 
under several conditions and a subsequent detailed analysis. 
Several replayings of each recorded speech sample were com- 
pared to typescripts and the judged disfluencies were 
categorized on two or more dimensions. Reliability co- 
efficients on a test-retest basis (above .90) were obtained 
for total disfluency count and rate of speech. 

An alternate procedure instructed an observer to 
rate a speech sample on an equal appearing scale of stutter- 



ing severity (Lewis and Sherman, 1951). An investigation 
comparing several rating scales and rater instructions 
(Cullinan, Prather, and Williams, 1965) estimated tliat four 
or more judges were necessary to obtain inter-^udge 
reliability coefficients above .90 for speecb samples of 20 
seconds' duration. Tbere is also a question as to whether 
or not rating periods of stuttering severity following these, 
procedures is adequate for a prediction of stuttering 
frequency. Sherman and Trotter (1956) reported correlations 
of approximately .60 between frequency and severity of 
individual moments of stuttering. They recommended that 
measures of frequency and severity of disfluency are both 
needed to define the speaker's disfluency. 

These data are cited to emphasize that currently 
available observer defined techniques of estimating dis- 
fluency are time consuming to the clinician or researcher. 
Less tedious alternatives involve reliability risks. An 
authority (Milisen, 1957) suggested these measures need not 
be highly accurate, and stressed disfluent behavior as being 
highly variable from period to period or from situation to 
situation. Recent research does not report such variability 
unless experimental contingencies were manipulated 
(Goldiamond, 1965). Perhaps observer techniques of measuring 
disfluency will of necessity be time consuming or vague until 
basic psychophysics advances substantially. Implicit in 



this statement is the assumption that correlates of observer 
defined disfluency exist. 

Hill (19A-A-,a,'b) reported comprehensive reviews of 
bio-chemical and physiological correlates of stuttering. 
For these two broad categories, his conclusions were 
essentially negative with respect to the existence of 
causally linked events. Subsequent research in these areas 
has been scant. Williams (1953) compared the muscle action 
potentials in stuttered and non-stuttered speech by electro- 
myographic procedures. He concluded that although the EMG 
pattern certainly reflected preceding motor neuron activity, 
he did not find sufficient evidence to imply stutterers and 
non-stutterers differ neuro-physiologically from one another, 

The acoustical differences between the speech of 
stutterers and normal speakers were reported by Travis 
(1927a). Using a phonophotographic technique, the speech 
of disfluent and fluent speakers was compared under condi- 
tions of 'non emotional prepositional' speaking. It was 
reported that disfluent speakers exhibited (1) marked pro- 
longations of 'tones,' (2) fluctuations of breath pressure 
preceding and following phonation, and (5) short vibrations 
before onset of voice wave. Certain disfluent speakers 
showed 'bizarre' waves in phonation curves which varied 
markedly in length. Groups of oscillations of high 
frequency but low amplitude and long series of oscillations 



8 

at approximately 500 cycles per second were also reported. 
None of these findings were conimonly found in tlie piiono- 
pliotograplis of tlie fluent speakers. 

A subsequent report (Travis, 1927b) compared the 
voices of stutterers and normal speakers under conditions 
of emotive and non-emotive producing stimuli. The stut- 
terers had more pitch variations than did the non-stutterers. 
After being subjected to emotion producing stimuli, the 
stutterers had less variability while the non-stutterers had 
more as compared to their respective baseline conditions. 

Adams (1955) designed a study to determine the 
existence of differences between pitch characteristics of 
stutterers and non-stutterers during conversation. Syl- 
lables were selected from speech samples obtained from 
groups of stutterers and fluent speakers. Recordings of 
these speech samples were submitted to phonophotographic 
analysis. Significantly smaller mean pitch inflections were 
observed for the stuttering group. Subjects from the desig- 
nated groups also recorded the sustained vowel (i), as in 
meet, at each mean pitch level. Stutterers exhibited 
limited variation in pitch and the more severe stutterers 
showed the fewest variations. These studies have been con- 
cerned with comparing acoustical measures of speech and 
sustained tones between groups of stutterers and normally 
fluent speakers. 



Bryngleson (1952) reported acoustical phonophoto- 
graphic analysis of vocal disturbances occurring during 
moments of stuttering for 17 adult stutterers. Plionopiioto- 
graphic records of the stutterer's voice during stuttering 
were reported to show (1) marked variation in the form, 
length, and intensity of consecutive waves; (2) marked 
reduction in tone variability; (5) a variety of isolated 
waves; (^) extreme variability in initial vocalization; and 
(5) abnormal endings to vocalization. These observations 
were made relative to findings reported in studies of the 
phonophotographic analysis of normal speech. 

The method for determining the moments of disfluency 
was not reported. If these citations represent a nearly 
complete survey of the literature on acoustical correlates 
of observer defined disfluency, decisions as to the rela- 
tive usefulness of acoustical correlates rest with future 

research. 

Bloodstein (19^^) investigated the relationship be- 
tween oral reading rate and stuttering severity. In these 
findings strong relationships between reading rate and 
disfluency and between reading rate and duration of dis- 
fluency were suggested. The reported relationships 
apparently held for the stutterers during moments of fluency. 
Similar findings have been reported by Roberts (1950), 
Robinson (1951) and Goldiamond (1965). Sander (1961) 



10 

reported a product moment correlation of .86 between dis- 
fluency and speaking rate. 

Tiie variability of frequency distributions of speech 
and silence events may pose a question. Will a stutterer 
with a judged high frequency of interjections have a dif- 
ferent frequency distribution pattern from that of fluent 
speakers? Travis (1927a) reported the frequency distribu- 
tion of speech events comparing a fluent speaker and a 
severe stutterer. Class intervals of 500 milliseconds and 
samples of conversational speech were used for the study. 
The stutterer exhibited fewer short speech events and sub- 
stantially more frequent long speech events. 

A paper presented at the 1958 American Speech and 
Hearing Association Convention (Roe and Derbyshire) reported 
systematic differences between stutterers and normal speak- 
ers for durational distributions of silence intervals during 
conversational speech. In it, a class interval size of 50 
milliseconds was utilized. Data were obtained by hand 
measuring photographs of cathode ray oscilloscope speech 
displays. The stutterers' conversational speech showed 
fewer intervals of short durations of silence and more 
frequent intervals of longer durations as compared to fluent 
speakers. 

Preliminary Research . The report by Travis and the 
paper by Roe and Derbyshire represent the extent of current 



11 



iniorma-bion concernirLg the systematic relationship hetween 
durational correlates and observer defined disfluencies. 
Noting this lack of information, this author did preliminary 
research designed to replicate the differences reported by 
Soe and Derbyshire. This preliminary investigation, utilizing 
an automatic analysis device, obtained further information 
concerning the freo^uency distributions of silence events which 
occurred during fluent and disfluent oral reading and related 
these data to disfluency frequency and reading time. 

Tape recordings of five adult fluent speakers and 
six stutterers were made. The chosen reading passage was 
read consecutively six times by each subject. Subjects were 
selected to provide a range of reading and disfluency rates. 
The tape recordings were played to an automatic device 
capable of classifying silence events into thirty-three 
class intervals with the lowest observable silence event be- 
ing .05 seconds. The device cumulatively recorded the 
number of silence events by length of duration. An observer 
listened to the recordings and tabulated the number of dis- 
fluencies. Reading time per passage was also obtained. The 
frequency distributions for the fluent subjects were plotted 
on a composite graph. The frequency distributions of silence 
events for the disfluent subjects were plotted individually, 
comparing each subject to himself on the several trials and 
to the composite graph of the fluent speakers. 



12 

Tiie curves for ciimulative frequency distributions 
of silence events of fluent subjects with th.e fastest 
reading times were approximately the shape of an inverted 
L. As oral reading time decreased, the point of inflection 
on the curve was more gradually approached, with the curves 
of the slower reading subjects exhibiting a greater abso- 
lute frequency of silence intervals. With these subjects, 
shifts in frequency distributions from trial to trial were 
not observed. 

The frequency distribution of silence events for the 
disfluent speakers differed quantitatively from trial to 
trial, between subjects, and from the composite curves of 
the fluent speakers. Disfluent speakers had fewer silence 
events below 120 milliseconds than did the fluent speakers. 
There was a tendency for the curves associated with the 
highest disfluency percentage to be the most dissimilar. 
These had characteristics of increased acceleration followed 
by decreased acceleration. As the disfluency percentage 
more closely approximated that of the fluent speakers, the 
curves of frequency distributions of silence events more 
nearly approximated the fluent subject's data. The cumula- 
tive frequency distributions of a disfluent subject, whose 
disfluency rate was within normal range, were comparable to 
the fluent speaker's composite curve for silence intervals. 
A detailed report of this preliminary research is included 
in Appendix A. 



15 

Frequency Distribution of Fluent Speecli . In recent 
years a number of investigators bave reported instruments 
for tlie automatic analysis of speech durations as they occur 
in connected speech samples (Hargreaves and Starkweather, 
1959 and Verzeano, 1950). These devices used voice-operated 
electronic circuits which detected and counted total number 
of speech intervals in a speech sample falling within a set 
range of durations. These have been accompanied by reports 
which justify ignoring silence events below .5 seconds 
(Hargreaves, I960 and Verzeano, 1951) as not being relevant 
to their experimental topics. The topics concerned dis- 
crimination among speech behavior in various environmental 

settings and tasks. 

Minifie (1965) reported a device capable of detecting 
speech or silence events in class intervals as short as ten 
milliseconds. A limitation of the device was the necessity 
of running each tape 52 times to obtain a cumulative distri- 
bution of speech and silence events for the speech samples 
contained. Using this analysis device, Minifie attempted 
to assay the effects of (1) instructions with respect to 
reading rate and vocal effort, (2) mean word length, and 
(5) oral reading versus impromptu speaking. Speech samples 
of twelve graduate students were used. Changes in oral 
reading rate were largely accounted for by fewer silence 
events of long durations such as would occur between phrases 



1^ 

and sentences. Instructions to increase vocal effort cor- 
related with detectable increases in the frequency of speech 
events associated with the duration of vowels. The converse 
was observed when the speakers were instructed to decrease 
vocal effort. Negotiable effects on frequency distributions 
for speech and silence events were reported for three dif- 
ferent reading passages which varied by mean word length 
measured in syllables. The effects of impromptu speaking 
versus baseline oral reading were observed by the frequency 
distribution of fewer silence events of short duration 
(125 milliseconds to 500 milliseconds), and by an increase 
in the longer durations of silence. 

It should be emphasized that the shape of the cumula- 
tive durational frequency curves for silence events approxi- 
mated those observed in the cited preliminary research for 
fluent subjects. In both the preliminary and Minifie's 
research, faster oral reading rates were associated with a 
sharp point of inflection and slower reading rates with a 
more gradual inflection point and greater frequencies of 
periods of silence. 

Generalization from these data is hazardous because 
cumulative durational distributions do not provide a straight- 
forward and readily interpretable method of dealing with 
subject to subject variability. Bach class interval is not 
only dependent on the count which occurs within a fixed time 



15 

range but also on events whicli occur in every class interval 
temporally before it. These unique plots were necessarily 
employed in tbe above studies because the automatic 
apparatus used in each investigation limited the time dura- 
tion of each class interval to unequal periods. These 
unequal periods seriously limited graphic and/or numerical 
presentation methods and analysis procedures. Subsequent 
research was proposed using instrumentation which would 
permit collection of data in class intervals of equal 
temporal values, thus allowing estimates sjnong and within 
subject variability at given points along the durational 
parameters of vocal behavior. 



CHAPTER II 

METHOD 

The procedures followed in this research may "be 
described in reference to selection of subjects, apparatus, 
recording procedures and measures of oral reading time and 
disfluency. 

Selection of Subjects 

Thirty-two male and thirty-two female young adults 
served as fluent subjects. They were obtained from a 
Behavioral Science course at the University of South Florida. 
Their ages ranged from 17 to 30 years. Any student who 
reported possessing a speech problem or demonstrated a 
speech problem to the experimenter was rejected as a subject. 
The young adult college population was selected for several 
reasons apart from availability. College age fluent 
speaJsers euid stutterers compare' favorably with respect to 
language ability (Steer, 1935). Compared to the young adult 
population as a whole, subjects selected on the basis of 
probable academic success could be expected to demonstrate 
relatively greater homogeneity in respect to many measures 
of vocal behavior. 

T\felve stutterers, two female and ten male, served 
as a disfluent speaking group. Their ages ranged from 18 

16 i 



17 

to 29 years. Tlie disflueat subjects were obtained from the 
University of Florida's Speecb and Hearing Clinics and from 
tbe Developmental Center at the University of South. Florida. 
All reported having a communication problem called stutter- ■ 
ing and had received a minimum of several months' treatment. 

Apparatus 

The frequency distributions for speech and silence 
events of the oral readings were obtained by playing tape 
recorded speech samples to a voice-operated relay which 
converted speech or silence to DC pulses. The pulses were 
fed to an electronic multiple-class time analyzer with 
fifteen class intervals, the last class interval being 
without an upper limit. 

The voice-operated relay and multiple-class time 
analyzer were treated to eliminate speech and silence 
events of durations less than 50 milliseconds. This de- 
cision was prompted by Minifie (1963) who reported a notch 
or gap in the distributions at the ^0-50 milliseconds time 
interval which caused him to conclude that events below A-0- 
50 milliseconds were not likely to change with speech 
behavior. He also reported that speech and silence events 
shorter than ^0 milliseconds contributed less than 3 per cent 
of the total speaking time. A practical argument for 
eliminating these durations was in the limitation of the 
apparatus which did not function reliably below 50 milli- 



18 

seconds. The time analyzer classified speecli or silence 
events into fourteen 50 millisecond class intervals. Dura- 
tions above 750 milliseconds were recorded in a fifteenth 
counter. Curves for the cumulative durational distribu- 
tions reported in the preliminary research by the author 
and by Minifie, became asymptomic beyond 600 milliseconds. 
Based on these data, the durations between 50 and 750 
milliseconds appeared to be the most productive portions of 
the frequency distributions for speech and silence events. 

The gain control of the voice-operated relay was set 
to operate at 100 millivolts for white noise and square 
waves of 250, 500, and 1000 cycles per second. The noise 
level of each tape played to the voice -operated relay was 
set within five millivolts of the voltage required to 
operate the relay for these signals. These measurements 
were made with a Hewlett Packard 400B voltmeter. 

Tape recordings of each speech sample were played to 
the durational analysis apparatus twice. Once to obtain 
the frequency distributions for speech events, and once to 
obtain the frequency distributions of silence events. 

Calibration of the durational analysis device was 
accomplished by presenting known time values of white noise 
to its input. The time values of these signals ranged from 
50 to 750 milliseconds. The internal clock of the Hewlett 
Packard 521A Electronic Counter, which is capable of 



19 

clocking events in 0.1 millisecond units, was used for ttie 
time reference. Repeated claecks of eacli class interval 
indicated tiie apparatus was functioning within tloree milli- 
seconds tolerance. 

Reliability of tlie durational analysis device was 
established by selecting at random sixteen taped speech 
samples and independently analyzing the results of each 
sample twice. Product-moment correlations were run and 
these results are reported in Appendix B, Table 10. 
Reliability coefficients for speech events ranged from .917 
at 500-5^9 milliseconds to .992 at 750 milliseconds and be- 
yond. The median correlation was .955 at 150-199 milli- 
seconds. For silence events, the reliability coefficients 
ranged from ,84^1- at ^50-499 milliseconds to .995 at 50-99 
milliseconds with the median correlation being .957 at 200- 
2^9 milliseconds. The durational analysis device used for 
this research can be commercially obtained from the Grason 
Stadler Company, V7est Concord, Massachusetts as (1) E7300A 
Voice-Operated Relay, (2) E5950A Multiple-Class Time 
Analyzer, and (5) EllOOD Power Supply. 

The tape recordings made at the University of South 
Florida and at the University of Florida were made in 
comparable Industrial Acoustics Company sound-treated rooms. 
All speech samples were recorded on a Vollensak T1500 tape 
recorder. The speed of the tape deck used was empirically 



20 

determined to be constant "between record and play-"back 
conditions -witliin 2 per cent. 

Recording Procedures 

Each subject was seated at a table in the sound- 
treated room with a microphone positioned approximately 18 
inches from his mouth. The experimenter, seated across 
from the subject, asked identifying information such as 
name,, age, level of education and marital status. The 
subject was then asked why he chose to attend college, what 
previous experience he had in recording his speech, and if 
he had a history of any speech problem. The purpose of this 
questioning was to accustom the subject to the experimental 
situation. The subject was then handed a copy of the 
'Arthur' passage (Fairbanks, 19^0) and told to read it 
orally as he ordinarily would . He v/as also cautioned to 
remain a constant distance from the microphone. These 
instructions followed those reported for the lov/a Speech 
Disfluency Test. During this reading, the volume control 
on the tape recorder was adjusted to the subject's speech 
intensity, and this also provided an opportunity for further 
adaptation to the speaking situation. Upon completion, a 
ten-second period of no oral activity in the recording room 
followed to allov; for adjustment of the noise level for the 
subsequent durational analysis. The subject was then handed 



21 

a copy of the 'average' reading passage constructed by 
Darley (19^0) and instructed to read it as he ordinarily 
would . He was again cautioned to remain a constant distance 
from the microphone. Upon completion of this reading, the 
fluent subjects made an appointment for the second recording 
session (Trial II). 

Two possible sources of variance which are routinely 
encountered in research involving significant sample size 
are the time of day at which the sessions are run and the 
sex of the experimenter in combination with the sex of the 
subject. Either or both factors could conceivably possess 
discriminative instruction value to the subject with respect 
to response rate or intensity (Staats and Staats, 1965). 
Time of day, in addition to conditioned excitory or in- 
hibitory factors, may relate indirectly to fatigue factors 
(Pavlov, 1927) which also may alter the response topology. 
The decision to vary the sex of the experimenters was based 
on cultural emphasis (Berelson and Steiner, 196^). There- 
fore, a male and a female Speech Pathologist were used as 
experimenters. Time of day was divided into four periods: 
(1) 8am-10am, (2) 10am-l2pm, (5) lpm-5pm, and (^) 3pm-5pm. 
The number of subjects run in each condition was as follows: 



22 



Male Experimenter 
Male Subject Female Subject 



Female Experimenter 

Male Subject Female Sub- 
ject 



8 am- 

10am- 

1pm- 

5pm- 



'4- 



4 
4 



4 

4 
4 



4 
4 
4 
4 



Oral Reading Time and Disfluency Measures 

Oral reading time was obtained by measuring tbe 
length of the recorded reading passage with a stop watch, 
Reading time was rounded to the closest 0.5 second. Dis- 
fluencies were marked by the experimenter on a copy of the 
passage as he listened to the recorded speech sample. For 
purposes of obtaining the total count, a disfluency was 
defined as an interjection or repetition of a sound, syllable, 
word or phrase. The repetition of a given word was counted 
as a single disfluency regardless of the number of times the 
word or portion of the word was repeated. Similarly, the 
interjection of a single word or of an entire phrase was 
counted as a single disfluency. This procedure was selected 
because recent research (Sander, 1961, and Siegel and Martin, 
1965) reported that it yields high reliability coefficients 
(above .90) between and within experimenters. Between and 
within experimenter reliability coefficients were obtained 
for twelve and sixteen speech samples respectively. 



25 

Reliability correlations were obtained for both, oral 
reading time and total disfluency frequency, Tliese results 
are presented in Appendix B, Table 11, The between and 
within experimenter reliability coefficients were observed 
to be above ,90 for reading time. The reliability coeffici- 
ents for frequency of disfluency were observed to be ,97 
between experimenters and .79 within experimenters, Tuthill 
(19^6) reported reliability coefficients of .72 as typical 
test-retest values for frequency of disfluency. 



] CHAPTEH III 

'i RESULTS 

The results of this research, are presented in refer- 
1 ence to reliability of individual and group measures; 
J comparison of fluent and disfluent speech samples; and 

effects of time of day and experimenter subject combinations. 
Each section will contain the information relevant to oral 
reading time and disfluency frequency, frequency distribu- 
tions of speech events, and frequency distributions of 
silence events. 

Reliability of Individual and Group Measures 

A purpose of this research was to obtain frequency 
distributions of speech events and silence events that 
occurred during oral reading for fluent speakers and to 
test the stability of these means on a test-retest basis. 
Means, standard deviations and correlations for Trials I and 

i II of fluent speakers were obtained for these measures. The 
reliability of the data was tested on an individual (cor- 

I relation) and group (t test) basis. 

I Oral Reading Time and Disfluency Frequency , The mean 

reading time for fluent speakers on Trial I was 95.01 seconds 
with a standard deviation of 9.17. S'or Trial II, the mean 

24 



I 



25 
reading time was 92,^1 seconds and tlie standard deviation 
was 7,96. Tlie correlation between Trials I and II for 
reading time was .9^5. S'or the mean difference between 
trials, tlie t ratio was 5,67 wbich. is significant beyond the 
,01 level of confidence. 

The mean of the total disfluency frequency count for 
these 64- fluent speakers on Trial I was 3.59 with a standard 
deviation of 2,51» and on Trial II 3.11 with a standard 
deviation of 2.33. The correlation between Trials I and II 
for disfluencj frequency was .607. For mean difference be- 
tween trials, the t ratio was 1,78, which failed to reach 
significance at the .05 level of confidence, 

frequency Distributions of Speech Events, For the 
purposes of this research, speech events were arbitrarily 
defined as vocalizations which transcended the noise level 
of the recording apparatus and exceeded a duration of 50 
milliseconds. Table 1 presents the means, standard devia- 
tions and correlations between Trial I and Trial II for 
speech events of fluent speakers. The mean frequency of 
speech events between 50-99 milliseconds for Trial I was 
6^.25 with a standard deviation of 13.56, and for Trial II 
64-. 81 with a standard deviation of 13.09. The mean frequency 
of speech events between 100-14-9 milliseconds for Trial I was 
52,30 with a standard deviation of 9.81, and for Trial II 
50,33 with a standard deviation of 9.12, In the third class 



26 



Ta'ble 1. Means, standard deviations and correlations of 
Trials I and II for frequency of speech events of 6^ 
fluent speakers. 



Time in 
milli- 
seconds 


Me 


an 


Standard 
Deviation 


Correlation 


Trial I 


Trial II 


Trial I 


Trial II 


r I II 


50- 99 


64.25 


64.81 


15.56 


15.09 


.715 


100-149 


52.50 


50.55 


9.81 


9.12 


.246 


150-199 


44,00 


44.15 


5.97 


7.58 


.150 


200-249 


29.5^ 


29.85 


6.02 


6.12 


.410 


250-299 


19.22 


19.42 


^.57 


4.57 


.125 


500-549 


15.55 


15.70 


4.82 


4.45 


.165 


550-599 


11.15 


11.89 


5.47 


^.55 


.511 


A.00-449 


7.75 


7.72 


5.61 


4.04 


.566 


450-499 


4.59 


4.28 


2.55 


2.49 


.279 


500-549 


2.98 


2.97 


1.97 


2.10 


.575 


550-599 


2.08 


1.85 


1.69 


1.56 


.270 


600-649 


1.65 


1.56 


1.69 


1.54 


.507 


650-699 


1.05 


, 1 . 20 


1.28 


1.21 


.241 


700-749 


.72 


.75 


.92 


.91 


.252 


750-X 


1.69 


1.50 


5.62 


1.50 


.154 



27 

interval, 150-199 milliseconds, the mean frequency of speech 
events was 4-4.00 for Trial I and 44.13 for Trial II. The 
standard deviations for these trials were 5.97 and 7.38 
respectively. This decrease in mean frequency of speech 
events continued through the twelfth class interval, 600- 
549 milliseconds, where the mean frequency was 1.53 with a 
standard deviation of 1.59 for Trial I, and 1.36 with a 
standard deviation of 1.3^ for Trial II. After this point, 
some decrease was observed but frequencies were low. 

Correlations between trials ranged from .713 at the 
50-99 millisecond class interval to .123 at the 250-299 
class interval. The median correlation was .270 which 
occurred at the 550-599 millisecond class interval. To test 
for a significant difference between means at each class 
interval, t tests for related measures were used. No 
significant mean differences were obtained. The moderate 
' to low correlations indicated some tendency for these sub- 
I jects individually to replicate, the temporal properties of 

J 

their speech events from trial to trial. The lack of 
I significance observed by t test procedures indicated that 

I these subjects as a group replicated durational properties 

1 

of speech events, 

Frequency Distributions of Silence Events . In this 
research, silence events were defined as periods occurring 
during connected speech where the noise level of the apparatus 



28 

was not transcended and possessed a duration in excess of 
50 milliseconds. The means, standard deviations and cor- 
relations between Trial I and Trial II for silence events 
of fluent speakers are presented in Table 2, The mean 
frequency of silence events between 50-90 milliseconds for 
Trial I was 103.02 with a standard deviation of 22.08. For 
Trial II the mean frequency of silence events was 106.56 
with a standard deviation of 17.90. The mean frequency of , 
silence events between 100-1^9 milliseconds for Trial I was 
60.02 with a standard deviation of 17«27 and for Trial II, 
a mean of 58.^7 with a standard deviation of I5.8I. The 
mean frequency of silence events at the 150-199 millisecond 
class interval for Trial I was 2^. ^8 with a standard devia- 
tion of 10.21 and for Trial II a mean of 22,78 with a 
standard deviation of 9.11. This decrease in mean frequency 
of silence events continued through the 4-00-^^9 milliseconds 
class interval where for Trial I the mean frequency was 2.81 
with a standard deviation of 1.92. The data remained 
asympotic until the fifteenth interval, 750 milliseconds and 
beyond, where for Trial I the mean frequency was 9.55 with 
a standard deviation of 4-, 75 and for Trial II 8,67 with a 
standard deviation of 4-. 35. Because this class interval had 
no upper limit, it was not comparable to the fourteen 
preceeding class intervals. 



29 



Table 2, Means, standard deviations and correlations of 
Trials I and II for frequency of silence events of 5^ 
fluent speakers. 



Time in 
milli- 
seconds 


Me 


an 


Standard 
Deviation 


Correlation 


Trial I 


Trial II 


Trial I 


Trial II 


r I II 


50- 99 


103.02 


106.36 


22.08 


17.90 


.624 


100-1^9 


60.02 


58.^7 


17.27 


13. 81 


.601 


150-199 


2^. ^8 


22.78 


10.21 


9.11 


.474 


200-2^9 


9.23 


8.56 


6.02 


4.96 


.297 


250-299 


^.8A- 


^.17 


3.39 


3.84 


.501 


300-3^9 


3.63 


2.91 


2.6^ 


2.70 


.209 


350-399 


3.16 


2.77 


2.50 


2.13 


.587 


400-^49 


2.81 


2.59 


2.01 


1.92 


.338 


^50-499 


3.33 


2.88 


2.02 


2.25 


.199 


500-5^9 


2.55 


2.58 


1.78 


1.79 


.228 


550-599 


2.53 


2.05 


1.81 


1.65 


.221 


500-6^9 


1.91 


2.17 


1.83 


1.60 


^.042 


650-599 


2.13 


1.73 


1.70 


1.44 


.137 


700-7^9 


1.61 


1.63 


1.22 


1.50 


.197 


750-2 


9.55* 


8.67* 


^.75 


4.35 


.806 



* 



Xj and x-j.^ differ beyond .05 level of confidence, 



30 

Correlations "between trials ranged from -.0^2 at 
th.e 600-649 milliseconds class interval to .806 at the 750 
milliseconds and "beyond class interval. The median cor- 
relation was .297 at the 200-2^9 milliseconds class interval. 
To test for a significant difference between means at each 
class interval, t tests for related measures were used. For 
the frequency of silence events above 750 milliseconds, the 
means were significantly different beyond the .05 level of 
confidence. 
Comparison of Fluent and Disfluent Speech Samples 

Contingent upon the observed stability of the mean 
estimates for frequency distributions of speech and silence 
events for fluent speakers, it was hypothesized: The 
durational data for disfluent speakers will deviate from 
the mean estimates obtained for the fluent speakers at one 
or more class intervals. 

Oral Reading; Time and Disfluency Frequency . The mean 
reading time for the disfluent speakers (stutterers) was 
229.25 seconds with a standard deviation of 168.78 as com- 
pared to a mean reading time of 92.62 seconds with a standard 
deviation of 11.80 for the fluent speakers. To determine 
the significance of the difference between these groups, a 
t test for independent measures was calculated. The results 
indicated the mean difference between these groups was 
significant at the .05 level of confidence. 



51 

0?lie mean disfluency frequency for tlie stutterers was 
'4-2.53 with a standard deviation of ^■4-. 12 as compared to 5.9^ 
with a standard deviation of 2.51 for the fluent speakers. 
The results of a t test for independent measures indicated 
the mean difference between these groups was significant at 
the .01 level of confidence. 

Frequency Distributions of Speech Events . The means, 
standard deviations and t tests comparing the' frequency 
distributions of speech events for stutterers and fluent 
speakers are presented in Table 3. Of the fourteen 50 milli- 
second class intervals for speech events, two were observed 
to be significant beyond the ,01 level of confidence. These 
intervals commenced with 150 and 200 milliseconds. Three 
additional class intervals were observed to be significant 
beyond the .05 level of confidence. These were the class 
intervals commencing with 100, 250, and 550 milliseconds. 
The remaining class intervals of speech events failed to 
discriminate between the fluent ' speakers and the stutterers. 
Where significance was observed, the mean frequency of 
speech events was higher for the stutterers than for the 
fluent speakers. 

* 

Frequency Distributions of Silence Events . Table 4 
presents the means, standard deviations, and t tests com- 
paring the frequency of silence events for stutterers as a 
group with fluent speakers. As observed from this table, 



32 



Table 5. Means, standard deviations and t tests comparing 
12 stutterers with 16 fluent speakers for frequency of 
speech, events. 



Time in 
milli- 
seconds 




Mean, 




Standard 
Deviation 


t of X-, - 
^2 


Stutterers 

< 


Fluent 
Speakers 


Stutterers 


Fluent 
Speakers 




50- 99 




76.^2 


62.75 


38.32 


13.87 


0.62 


100-1^9 




70.25 


^6.31 


29.07 


9.06 


2.65* 


150-199 




60.67 


^1.69 


15.19 


5.64 


3.95** 


200-2^9 




50.17 


30.06 


19.03 


6.87 


3.35** 


250-299 




32.58 


19.63 


16.09 


5.3^ 


2.57* 


500-3^9 




25.08 


16.63 


12.8A- 


6.18 


2.02 


350-399 




19.^2 


9.69 


12.61 


3.03 


2.51* 


A-00-^49 




13.75 


8.38 


11.40 


4.70 


1.47 


^50-^99 




7.83 


^-56 


6.63 


5.27 


1.51 


500-5^9 




7.17 


2.9^ 


6.78 


1.69 


2.02 


550-599 




^.92 


2.06 


5.29 


1.95 


1.71 


600-6^9 




3.17 


1.56 


3.89 


1.79 


1.28 


650-699 




2.17 


1.25 


3.67 


1.57 


0.52 


700-7^9 




1.58 


0.9^ 


1.38 


.93 


1.55 


750~x 




2.58 


1.31 


4.07 


1.7^ 


0.64 


t . 


05 


(df = 26) 


= 2.06 








t . 


01 


(df = 26) 


= 2.78 









35 



Table 4-. Means, standard deviations and t tests comparing 
12 stutterers with. 16 fluent speakers for frequency of 
silence events. 



Time in 
milli- 
seconds 




Mean 




Standard 
Deviation 


t of X-, - 
^2 


Stutterers Fluent 
Speakers 


Stutterers 


Fluent 
Speakers 




50- 99 




107.^2 




101.75 


44.20 


27.58 


0.57 


100-1^9 




63.83 




55.56 


18.68 


17.82 


1.14 


150-199 




39.50 




22.31 


18.37 


9.24 


2.85** 


200-24-9 




22.67 




8.9^ 


15.58 


5.89 


2.85** 


250-299 




12.92 




5.19 


8.40 


4.46 


2.78** 


500-3^9 




10.92 




3.25 


8.28 


2.27 


2.98** 


350-399 




7.25 




3.31 


6.48 


2.47 


1.91 


^00-^^49 




7.67 




2.38 


5.80 


1.96 


2.91** 


^50-^99 




6.25 




3.06 


5.48 


1.98 


1.84 


500-5^9 




6.75 




2.69 


5.45 


1.82 


2.37* 


550-599 




5.^2 




2A^ 


4.25 


1.93 


2.18* 


600-6^9 




^.83 




1.38 


4.16 


1.09 


2.70* 


550-699 




6.08 




2.15 


5.50 


1.78 


1.70 


700-7^9 




^.67 




2.00 


4.19 


1.32 


2.05 


750-X 




52.25 




9.13 


16.68 


4.11 


2.58* 


* 
t 


.05 


(df = 


26) 


= 2.06 








t 


.01 


(df = 


26) 


= 2.78 









four of tlie fifteen class intervals were significant beyond 
the .01 level of confidence. These intervals commenced 
with 150 5 200, 250s and 300 milliseconds. An additional 
four class intervals were significant beyond the .05 level 
of confidence. These were the intervals commencing with 
500, 550 J 600, and 750 milliseconds. In each significant 
class interval, the mean frequency of silence events was 
greater for the stutterers than for the fluent speakers. 

Effects of Time of Day and Experiment er - Sub.ject Combinations 

Two purposes of this research were to test the 
following hypotheses: (1) The time of day during which 
subjects are run does not significantly influence frequency 
distributions of speech and silence events, and (2) The sex 
of the experimenter in combination with sex of the subject 
does not significantly influence frequency distributions of 
speech and silence events, 

A two-dimensional analysis of variance was used, 
treating time of day and sex of experimenter in combi23.ation 
with sex of subject as main effects. An analysis of vari- 
ance was performed for reading time, disfluency frequency 
and each of the fifteen class intervals for speech and 
silence events. 

For the four analyses of variance treating the effects 
of the experimental variables on oral reading time and dis- 



35 

fluency frequency, non-significant P ratios were uniformly 
observed. ' ■ ^ 

Sixty separate analyses of variance were obtained for 
tile class intervals of speech and silence events. Six 
significant P ratios at the .05 level of confidence were 
obtained for speech events and six significant P ratios at 
the .05 level of confidence were obtained for silence events. 
The data v/ere inspected for potential patterns of signifi- 
cance. Each significant F ratio failed to replicate itself 
with respect to significance level on its comparable trial. 
Other patterns considered were significance l>j trial and 
significance by variable. Such inspections failed to 
discern a rational pattern of significance. From the ob- 
tained 180 F ratios, by chance, nine may be expected to be 
significant beyond the .05 level of confidence and two 
significant beyond the .01 level of confidence. Therefore, 
the observed significances may reasonably be attributed to 
chance. Summary tables for these analyses are contained in 
Appendix B, 



CHAPTEE IV 
DISCUSSION 

The research findings of major importance were the 
significant differences observed "between stutterers and 
fluent speakers for frequency distributions of both speech 
and silence events. It was hypothesized that because 
stutterers use more time to read a set passage than do 
fluent speakers, at least one class interval of speech or 
silence events would significantly discriminate between 
stutterers and fluent speakers. Pive class intervals of 
speech events were found to significantly discriminate be- 
tween groups of fluent speakers and stutterers. Mne class 
intervals of silence events discriminated between these 

groups, 

The durational properties of vowels and syllables are 
reported to range from approximately 100 to '^-OO milliseconds 
(Black, 19^1-9; House, 1961; Sharf, 1962). In the present 
research the 50 millisecond class intervals of speech events 
whose lower limits were 100, 150, 200, 250, and 350 milli- 
seconds statistically discriminated between fluent speakers 
and stutterers. The durational properties of vowels and 
syllables may relate to observer defined sub-classifications 

36 



37 

01 disfluency wb.ich include interjections, part word 
repetitions 5 and x-zord repetitions (Johnson, 1951; Young, 
1951). At each, significant class interval, the mean for the 
stuttering group v/as greater than for the fluent speaking 
group. The frequency distributions of speech events for 
each subject v/ere determined by an automated durational 
analysis device. These findings suggested the vocal aspects 
of socially defined disfluency may be amenable to objective 
quantification which results from machine procedures* 
Socially defined disfluency may also possess acoustic 
properties v/hich differ from fluent speakers (Bryngelson, 
1952)1 however, the above quantification applies only to 
the durational aspects of vocal emission. 

The findings relative to speech events suggested that 
stutterers emit extraneous vocal behavior during oral read- 
ing. If the extraneous vocal behavior is temporally 
separated from other vocal behavior^ it would be expected 
to be reflected in the frequency distribution of silence 
events also. Such temporal separations were indicated by 
the presence of nine significant class intervals of silence 
events which discriminated between the stutterers and 
fluent speakers. These were the class intervals whose 
lower limits were 150, 200, 250, pGO, ^00, 5OO, 550, 500, 
and 750 milliseconds. At each significant class interval, 
the mean of the stuttering group exceeded that of the fluent 



38 

speakers. Analysis of the preliminarj research data 
(Appendix A) comparing stutterers to fluent speakers sug- 
gested the possibility of these findings* Roe and 
Derbyshire (1958) presented anecdotal material which 
supported their suggestion of the possibility of differences 
in this dimension between fluent speakers and stutterers. 
In addition to advancing the proposition that temporal 
separation between extraneous vocal behavior accounts for 
the elevation in the frequency count of silence events, 
there are other factors that may relate to the increase of 
silence events. Clinical note has been made (Villiams, 1957) 
of an inhibitory or 'heel dragging' quality in the vocal 
behavior of stutterers, Wendahl and Cole (1951) reported 
listeners accurately discriminated between segments of 
stutterers' fluent speech and segments of fluent speakers' 
speech. They reported that the listeners relied in part on 
rate of speech to discriminate between the stuttering and 
fluent groups. If these findings are accurate, analysis of 
the frequency distribution for speech events of such edited 
samples of stuttered speech may not exhibit differences 
from segments of fluent speakers' speech. However, these 
stuttered speech samples with the moments of stuttering 
removed could be expected to exhibit differences in the 
I frequency distribution of silence events. This proposition 

relies on the assumption that the durational properties of 
vocal behavior are fixed by the content of the communication. 



39 

Excessive prolongations of speech elements enter into th.e 
social definition of disfluency. Two propositions have been 
advanced to account for the elevation of the frequency of 
silence events for the stuttering group. These were temporal 
separation between extraneous vocal behavior emitted and 
differences in the temporal spacing of the acoustic element. 
The resolution of these propositions must rely on subse- 
quent research, 

A purpose of this research was to establish estimates 
of the reliability of frequency distributions for speech 
and silence events of fluent speai:ers. On a test-retest 
basis, sufficiently stable reliability was observed to per- 
mit group comparisons, \-Jhile there Viras a tendency, with 
the procedures employed, for the fluent speakers to approxi- 
mate the durational characteristics of their vocal behavior 
on a test-retest basis, the reliability coefficients were 
not of sufficient magnitude to permit accurate comparison of 
individuals to the group. 

Group reliability was assessed by using t tests on a 
test-retest basis for the fluent speakers. For the fifteen 
class intervals of speech events, t tests for related 
measures indicated no significant differences between the 
means for Trials I and II. It will be recalled that the 
trials were separated by at least 24- hours. For fourteen 
class intervals of silence events, t tests for related 



^0 

measures irLdicated no significant differences between tlie 
means for Trials I and II. For the class interval whicli 
connted the frequency of silence events of 750 milliseconds 
and beyond, significance was observed at the .05 level of 
confidence. Two possible explanations are tenable. From 
30 t tests, at least one could be expected to be significant 
by chance. Secondly, the direction of the mean difference 
may. relate to the significant difference obtained between 
reading times for Trials I and II. For both reading time 
and frequency of silence events, the mean of Trial II was 
lower. This possible difference may support Minifie's 
(1963) conclusion that changes in reading time were largely 
accounted for by relatively few silence events of long 
durations. The lack of significance between Trials I and 

* 

II for the other respective class intervals of speech and 
silence events indicated sufficient reliability for group 
comparison. 

Assessment of individual reliability of speech and 
silence events was made by calculating reliability coeffici- 
ents for each class interval of speech and silence events. 
These reliability coefficients ranged from low to moderate 
values. As measured, it may be inferred there vras a low to 
moderate tendency for these. classes of vocal behavior to 
repeat when experimental conditions remained constant. The 
reliability coefficients do not approximate the necessary 
values (.90) to warrant prediction of individual behavior 
on these measures. 



41 

statistical treatment of tne frequency distributions 
of speecli and silence events for tlie experimental variables 
of the time of day and experimenter-subject combinations 
indicated tlie observed differences could reasonably be 
attributed to cbance. These statistical analyses indicated 
the experimenter-subject combinations and time of day vari- 
ables as measured are not factors of measurable importance 
to the frequency distributions of speech and silence events. 

Implications for Application and Further Research 

Clinically, Speech Pathologists are concerned with 
the behavior of stutterers as individuals rather than as a 
group. It was therefore appropriate to consider the data 
for the stuttering subjects individually. This was con- 
veniently presented by utilizing Z score techniques. The 
formula used for converting the raw frequency distribution 

data to Z score form was as follows: 2_Z_S (McNemar, 1955). 

o 

Where x stands for the observed frequency of a stutterer's 
frequency of events at a given class interval, x stands for 
the mean of the fluent speakers for Trial I, and tf stands 
for the standard deviation of the fluent speakers. The Z 
score procedure permitted an expression of an individual 
stutterer's deviations from the fluent speakez^s means at 
the respective class intervals, for speech and silence events. 

For the speech and silence intervals which dis- 
criminated between the fluent and stuttering groups, the Z 



^2 

scores were computed for the twelve stutterers and plotted 
in profile form. Cursory analysis of these profiles indi- 
cated the following: (1) when the disfluency frequency of 
these suhQects was within the range of fluent speakers 
(Johnson, 1951) the Z scores for the significant speech and 
silence intervals were within three standard deviations of 
the mean for fluent subjects; (2) when the disfluency 
frequency was above that of the range for fluent subjects 
the Z scores for the significant speech and silence inter- 
vals were beyond three standard deviations of the means for 
fluent subjects; (3) with the more severe stutterers, the Z 
score deviations appeared to be proportional to the observed 
disfluency frequency; (^) within the stuttering subjects 
there were a number of different observer defined patterns 
of disfluency; and (5) the Z score profiles also appeared to 
exhibit differences among disfluent subjects. These data 
are presented in Appendix C. 

It would be hazardous to be definitive about these 
individual analyses. The best available estimate of the 
standard error of these Z scores is the standard deviation 
of the group (McRemar, 1955)- This is due to certain low 
coefficients of reliability observed in the previous portions 
of this research. Also, the disfluent sample was limited 
in number of speakers. 

Refinement of the procedures employed will be neces- 
sary before an application of the technique indicated above 



^5 

can be utilized with precision. Subsequent researcb 
questions should be directed toward evolving procedures 
which will produce reliability coefficients of sufficient 
magnitude. Achievement of high test-retest reliability 
will permit definitive statements regarding the durational 
properties of an individual's vocal behavior. A parsi- 
monious first step towards this goal would be to investigate 
reliability coefficients as a function of the number of 
responses required from each speaker. 

Assuming adequate reliability is achieved, the basic 
technique of automated analysis of frequency distributions 
of speech and silence events may offer support for the 
stuttering specialist. Such procedures could lead to rapid 
and reliable evaluations of disfluency which would not be 
subject to observer bias. The currently employed observer 
defined procedures for defining extent and type of dis- 
fluent behavior are extremely time consuming. Also, when 
the Speech Pathologist is serving as both evaluator and 
clinician, bias relative to progress ir. -rherapy is possible. 
Automated machine pr-ocedures for defining; extent and type 
of disfluencies could be a valuable adjuno-u to clinical 
judgment. 

Future research could provide a means to convert 
norms for fluent vocal behavior to rate measures and program 
these norms into an electronic device which would provide 



moment to moment statements as to ttie relative fluency of 
a speaker. Such an electronic device could "be a useful tool 
for behavioral modification. Response contingent conse- 
quences for socially defined disfluency have "been reported 
to increase or decrease the rate of disfluency depending 
on whether the disfluent "behavior was reinforced or punished 
(Flanagan, Goldiamond, and Azrin, 1958 and 1959; Goldiamond, 
1955; Siegel and Martin, 1965; Leach, 1965). Such an 
electronic device could then conceivahly program reinforce- 
ment for fluent behavior. 



CHAPTER V 
SUMMAEY 

Tiie purposes of this researcli were to obtain variance 
estimates of frequency distributions of speech, and silence 
events wbicli occur during oral reading of fluent speakers, 
to assay the reliability of these frequency distributions 
on a test-retest basis and to determine the effects of 
experimenter-subject combinations and time of day variables 
on these measures. A major purpose was to compare frequency 
distributions of durational properties of oral reading for 
stutterers and fluent speakers. 

Tape recorded speech samples were obtained from 52 
male and 52 female young adult fluent speakers on two 
occasions separated by at least 2^ hours. These two trials 
provided the data for test-retest reliability estimates. 
The time of day and sex of experimenter were programmed in a 
manner to permit assessment of these variables on the 
frequency distributions of speech and silence events. Tape 
recorded speech samples were also obtained from 12 young 
adult stutterers. 

Connected speech was treated as a series of alter- 
nating speech and silence events with varying durations. 
Speech events were defined as vocalizations which transcended 

^5 



^6 

tiie noise level of the recording apparatus and exceeded a 
duration of 50 milliseconds. Silence events were defined 
as periods during conjiected speech where the noise level of 
the apparatus was not transcended and exceeded a duration 
of 50 milliseconds. The speech and silence events which 
occurred during these tape recorded speech samples were 
counted and tabulated by their durations. These data were 
assigned to class intervals which permitted construction of 
frequency distributions of speech and silence events. A 
total of fifteen class intervals were used, fourteen having 
a period of 50 milliseconds and the fifteenth counting all 
events exceeding durations of 750 milliseconds. 

The analysis of the results suggested that the 
following statements are warranted. 

1. Variance estimates of ■ durational distributions 
of speech and silence intervals have been 
empirically demonstrated to have sufficient 
reliability for group comparison. 

2, Experimenter-subject combinations and time of day 
variables were not factors of measurable impor- 
tance with respect to reading time, disfluency 
frequency, and frequency distributions of speech 
and silence events, 

3« Several class intervals of speech and silence 
events were found to discriminate significantly 
between groups of stutterers and fluent speakers. 

The class intervals of speech events which signifi- 
cantly discriminated between groups of stutterers and fluent 
speakers were those associated with the durations of vowels 



^7 

and syllables. The class intervals of silence events which 
significantly discriminated between groups of stutterers 
and fluent speakers may relate to the temporal separation 
of extraneous vocal behavior which may be socially defined 
as disfluency. These significant silence intervals may 
also relate to the clinically noted inhibitory or 'heel 
dragging' effect reported for stutterers. The discussion 
considered possible implications for further research and 
application of these findings. 



APPENDICES 



APPEiraiX A 

PRELIMINARY RESEARCH: DURATIONAL PROPERTIES OE SILENCE 
INTERVALS DURING ORAL READING 



Tliis investigation was designed to obtain information 
concerning tlie durational distributions of silence intervals 
which occur during disfluent and fluent oral reading and to 
relate these data to disfluency and reading rates. Dura- 
tional distributions are considered formal aspects of verbal 
behavior which can be made explicit by machine procedures. 

Procedures 

General Procedure . Tape recordings were made of 
adult normal speakers and of stutterers as a passage was 
consecutively read six times. The subjects were selected to 
provide a wide range of reading and disfluency rates. 

The tape recordings of the speech samples were played 
to an analysis device capable of classifying pauses into 33 
durations, with the lowest duration being .05 seconds. The 
device cumulatively recorded the number of silence inter- 
vals by durational categories. The reading time per passage 
was obtained with a stop watch. Frequency of disfluency was 
recorded by an observer who listened to the tape recordings. 
The obtained durational distributions were plotted 
j graphically and compared to disfluency frequency and reading 

rate. 

^9 



50 

A detailed statement of procedures and apparatus 
follows. 

Selection of Subjects. Five normal- speaking college 
students, ages ranging from 21 to 5^ years, were selected to 
provide a "base or wliat migbt be considered usual performance 
for this population. Tliese subjects reported no training in 
speaking or oral reading with, the exception of an intro- 
ductory speech course. 

Six subjects who had been diagnosed as stutterers by 
college speech clinics were also rim. Their ages ranged 
from 20 to 2? years. 

The rates of disfluency of stuttering subjects have 
been reported to change markedly with successive readings of 
the same material (Johnson, 1957). Tlie decrement in dis- 
fluency rate which occurs with successive readings of the 
same material, provided a rationale for each subject to 
serve as his own control with all conditions constant with 
the exception of trial number. Normally fluent subjects 
have also been reported (Starbuck and Steer, 1955) to ex- 
hibit attenuation of disfluency rate with successive read- 
ings of the same material. The differences in attenuation 
rate, however, were reported to be considerably fewer than 
those for stutterers. 



..'Suu--.~.i; .^Tw^v»i. 



51 

Recording Conditions , Speech was recorded in iso- 
lated rooms regularly used for this purpose. The recording 
equipment was in an adjoining room. Recordings were made 
in the evening when only an experimenter and the subject 
were present. 

Instructions to Subjects . The subject was seated at 
a table before the microphone and shown the text he was to 
read. He was instructed that he would read the passage six 
times. When signalled, he gave his name, the trial number, 
counted to ten out loud, and then after a pause began 
reading. He was also instructed to take breaks only between 
readings of the passage and also to avoid rattling the 
paper or shifting his position. Answers to any questions 
regarding the purpose of the research were deferred to the 
end of the session. 

Reading Passage . The reading passage was selected 
from The IJational Geographic and contained 102^ words. 
Sentences containing infrequently used names or words were 
eliminated. The passage was typed double spaced and each 
subject read from a ditto copy. 

Definition of Disfluency . The experimenter listened 
to the recorded tapes twice and recorded each instance of 
disfluency for both runs. A disfluency was defined as any 
break, excessive pause, prolongation or repetition of the 
flow of speech. 



52 

^Jg^i^P; of Reading Rate . The time lapse from tlie 
first to the last word of each reading of the; passage was 
timed manually using a .10 second stop watch. Time was 
rounded to the closest second. Five reliability checks 
indicated comparable times within .50 seconds. 

Apparatus . An electro-mechanical device utilizing 
relay attack time v/as used to time silence durations. When 
the voice-operated relay turned to the normally closed 
position, a count was recorded on the first counter and a 
current was applied to the coil of the first of 32 relays. 
yhen this relay made contact through its normally open 
points, a count was recorded in the second counter and 
current was applied to the coil of dumber 2 relay, and the 
process repeated for as long as the silence interval lasted 
or until all 32 relays were operative. Since relay attack 
varied with voltage, one voltage, 20 VDC, was used through- • 
out. Attack time variability for each relay did not exceed 
.001 second. At this voltage, the characteristic attack 
time was close to .030 second. A disadvantage of the 
apparatus was that not all 55 class intervals were of the 
same duration. 

All AG voltage inputs were run from constant voltage 
regulators which supplied 115 VAC. The tape recordings 
were played on an Ampex 601, a single track machine at 7-1/2 
inches per second. From the tape recorder, a 500 ohm output 



53 

was connected to a Hewlett Packard 5 watt 110 db attenuator, 
Model 350A, and then to an. Allison Laboratory band pass 
filter. Model 2A. The filter was set to pass between 150 
and 5600 cycles per second. The output of the filter was 
fed to a Hunter voice-operated relay and was monitored by 
a millivolt meter (10 mv full scale). The average peak 
intensities of speech for the various tapes were balanced by 
the attenuator to read between 2 and 3 millivolts on the 
meter. It was found that the speech intensity varied from 
recording to recording. No systematic shifts in speech 
intensity were observed during the reading of a passage. 
The sensitivity control of the voice-operated relay was set 
at the maximum sensitivity level. Measurement of attack 
release time of the voice-operated relay indicated .010 
second attack time and .050 second release time. 

Durations Used . A. 20 VDC ground was connected to the 
common pole on the voice-operated relay. Its normally 
closed contacts were connected to a pulse former and to the 
coil of the first relay of the timing circuit. The pulse 
former required a .006 second pulse to operate and in turn 
delivered a .01^ second pulse to the first counter. The 
Sedeco counters which were used required a .012 second pulse 
to operate. Hence, Counter 1 recorded all silence intervals 
over .056 seconds in duration. 



i if I- * , *li 4 :. . 



5^ 

Vlien the first relay (Clare DFDT telephone type) 
made contact., normally open, it delivered 30 VDC voltage 
through oi:ie set of contacts to ohe second pulse former 
which in warn fired Counter 2. The time di:l:"erance between 
the activation of Counter 1 and Counter 2 v/as .035 second. 
Thus,, Counter 2 recorded all silence intervale :/er .091 
seconds in length. Through the other set of con "acts on 
Helay 1, 20 VDC was delivered to the coil on Relay 2. The 
process described would then repeat through the remaining 
relays and counters. The final counter recorded durations 
of one second or longer. 

The analysis device was calibrated through the use of 
a timing circuit which delivered pulses of known durations. 
The calibration procedure was as follows. The voice-opera- 
ted relay was replaced by the calibration timing circuit. 
Pulses of one second duration were then sent to the relay 
coil which was adjusted iso that a pulse of one second dura- 
tion would just cause the last counter, Number 33, to record. 
y^iS Kiiis^ ¥£i schigysd. the celibratlon tiKin«r circuit was 
adgH-sted to produce a pulse in the rangg &i the presesdihg 
counter, Number 32, until its firing time was established 
and the process then repeated for each of the remaining 
counters. Each day during the running of data,, the last 
counter was recalibrated and several of the other counters 
were checked. 



55 

Reliability of the analysis device was establislied 
by playing tlie same tape to ttie analysis device four times, 
lable 5 shows the results of durational distributions of 
silence intervals for four runs of the same tape-recorded 
passage. The first row represents the frequency of silence 
intervals which exceeded .091 seconds, and the last row 
representing the number of pauses that exceeded I.050 
seconds. The greatest difference in frequencies between 
successive runs of the same tape did not exceed 5 per cent, 
except in those relays where the count was small. 

ii'oeiSiiag of Sata« Eaoii tapi-r^sorded pa^sag© wae 
played through the analysis device twice. Accordingly, two 
durational distributions of silence intervals were obtained 
for each sample. The differences between the two samples 
were within the order of difference reported for the 
reliability of the analysis device. The mean of the two 
runs was used to obtain a single datum point for each class 
interval of silence durations, 

Results 

Table 6 shows the oral reading rates for the normal 
subject by speaker and trial, A comparison of these data 
to a normative study (Darley, 19^0) of the oral reading rate 
for college students provided an estimate of the normalcy 
of the reading rates of the subjects depicted in Table 6, 



56 



Table 5. Number of silence intervals recorded at eacii 
dtiration, when same tape was run four times. 



Relay 


Silence 


Run 


Sun 


Run 


Run, 


Difference 


% Error 


Length 


X 


2 


5 


4 






(msec) 














1. 


56 


941 


949 


947 


929 


20 


2 


2. 


91 


706 


701 


719 


705 


18 


3 


5. 


121 


575 


580 


591 


575 


16 


4 


^. 


153 


455 


423 


438 


420 


18 


4 


5. 


186 


344 


340 


3^9 


534 


15 


4 


5. 


217 


314 


512 


515 


507 


8 


5 


7. 


2^3 


299 


500 


298 


292 


8 


3 


8. 


272 


284 


285 


282 


279 


5 


2 


9. 


300 


276 


276 


274 


274 


2 


1 


10. 


552 


268 


265 


267 


268 


3 


1 


11. 


365 


260 


257 


259 


262 


5 


2 


12. 


595 


250 


245 


246 


248 


4 


2 


15. 


^2Q 


236 


256 


257 


239 


3 


1 


1^. 


461 


227 


225 


227 


228 


3 


1 


15. 


^95 


217 


214 


215 


212 


5 


2 


16, 


524 


208 


206 


208 


204 


4 


2 


17. 


559 


191 


188 


193 


192 


5 


3 


18, 


590 


184 


178 


179 


179 


6 


3 


19. 


622 


171 


166 


166 


165 


6 


4 


20. 


656 


156 


149 


152 


149 


7 


5 


21. 


690 


143 


137 


141 


139 


6- 


4 


22, 


725 


138 


132 


155 


130 


8 


6 


23. 


755 


128 


123 


124 


120 


8 


7 


24. 


786 


120 


113 


112 


115 


8 


7 


25. 


822 


109 


107 


109 


106 


3 


3 


26. 


852 


108 


105 


104 


104 


5 


5 


27. 


881 


102 


99 


99 


100 


5 


5 


28. 


905 


96 


92 


95 


92 


4 


4 


29. 


929 


92 


B'? 


90 


90 


5 


6 


30. 


955 


88 


87 


85 


87 


3 


4 


31. 


988 


83 


80 


80 


82 


3 


4 


32. 


1020 


80 


?4 


73 


77 


7 


10 


33. 


1050 


76 


71 


71 


73 


5 


7 



57 



Table 6. Oral reading rate for normal subjects expressed 
in words per minute. 

Subjects Trials 

I II III IV V VI Mean 

1 159.5 168.9 16^.7 16^.5 165.0 161.5 160.6 

2 • 160.0 160.0 165.1 165.2 165.2 162.7 162.7 

3 160.4 188.9 192.7 189.1 198.8 198.8 188.1 
tv 161.7 178.1 179.6 178.5 188.9 191.1 179.7 
5 190.5 190.5 187.9 186.2 190.5 187.5 176.0 

Mean 162.5 177.5 177.6 176.7 181.7 180.2 176.0 



58 

The first trial of these data was used for comparison with 
Barley's norms. This trial represents the reading of over 
one thousand words per subject, while Darley sampled 500 
words per subject. For Trial I, a mean of 162.5 words per 
I minute with a standard deviation of 16.5 was obtained. 
Darley reported a mean of 167.5 words per minute with a 
standard deviation of 16.2 for 200 college students. Con- 
sidering the differences in exact content of the reading 
passages and the respective lengths of 1,000 and 500 words, 
the similarity appears more remarkable than the mean 
difference. 

Inspection of the means by trials suggested a gradual 
increase in oral reading rate, 162.5 v/ords per minute on 
Trial I to 180.2 words per minute on Trial VI. To evaluate 
the significance of this observation, a rank order Chi- 
square technique (Wilcoxon, 19^9) was selected. The result 
of this analysis indicated this distribution of trials by 
subjects could have occurred approximately one out of five 
times by chance. Gibbons, Winchester and Krebs (1958) found 
that sustained oral reading does not result in statistically 
significant temporal variation but rather a uniform rate of 
speaking occurs. 

Inspection of oral reading rate measures by subject 
suggested that subjects differed from each other although 
there was overlap. 



59 

The tape recordings of tlie subjects v/ere played to 
an experimenter wlao marked disfluencies on a copy of the 
reading passage. Tahle 7 presents the percentages of 
disfluencies for the normal subjects by trial. The mean 
disfluency percentage for Trial I was 1 per cent with a 
range of 1/2 to 1-1/2 per cent. Norms (Johnson, 1961) for 
disfluency rates of fluent male college students were re- 
ported. A disfluency rate of 1 per cent was reported as 
typical during conditions of oral reading of a factual 
passage. With respect to this measure, the current sample 
was considered comparable at least in respect to central 
tendency. 

Inspection of means by trial suggested a decrement 
in the percentage of disfluency with repeated reading of 
the passage. Starbuck and Steer (1953) reported this 
adaptation phenomenon for twenty- tv/o fluent college students. 
To assist in an evaluation of these apparently collabo- 
rative findings of the present study, rank order Chi-square 
analysis of trials by subject was employed. This test 
indicated that decrement in disfluency rate could occur by 
chance less than .007 times. These findings suggested that 
the subjects in the current study were comparable with the 
fluent subjects studied by Starbuck and Steer with respect 
to progressive decrement in disfluency with successive 
reading of the same material. 



60 



TalDle 7, Percent of disfluent words for normal subjects. 



Su'baec'ts Trials 

I II III IV V VI Mean 



1 0.927 0.732 0.2^4- 0.590 0.2^4 0.195 0,^55 

2 0.927 1.025 0.927 0.^88 0.590 0.65^ 0.732 

3 1.367 0.976 0.732 1.025 0.683 0.537 0.887 
/}- 1.^6^ 1.269 1.123 0.927 0.781 0.3^1 0.984- 
3 0.^39 0.63^ 0.292 0.048 0.292 0.146 0.308 

Mean 1.025 0.927 0.664 0.576 0.478 0.371 0.675 



61 

To assay the significance of the range of disfluency 
exhibited "by the respective subjects, Chi-sguare statistical 
analysis was again employed. The results, probability of 
less than .002, indicated that the subjects exhibited dis- 
fluency rates different from each other and the ordinal 
relationship remained approximately constant through the 
decrement in disfluencies occurring with adaptation. Con- 
cerning the typical properties of these subjects, it should 
be noted that the range of disfluencies falls v;ithin the 
first to seventh decile of the norms for comparable groups 
(Johnson, 1951). 

Analysis of the relation between oral reading rate 
(Table 6) and disfluency rate (Table 7) indicates the re- 
lationship for these fluent speakers is not strong. On 
Trial I, the fastest reader S~5 (190 trpm) had the fewest 
disfluencies (.5 per cent). The slowest reader, S-1 (139 
vrpm) emitted 1 per cent disfluencies, while the subjects in 
close approximation of the mean words per minute exhibited 
the greatest percentage of disfluencies. For stutterers, 
Sander (1951) reported a strong relationship between dis- 
fluency and oral reading rate (Pearson's r of .85). From 
the data presented here, it appears that for fluent subjects 
there is a greater independence between disfluency and oral 
reading rates. 

Table S lists the oral reading rate in words per 
minute for the stuttering subjects by trial. For Trial I, 



62 



Table 8. Oral reading rate for stuttering subjects 

expressed in words per minute. 

Subjects Trials 

I II III IV V VI Mean 

1 63.8 78.8 8^.9 95.2 92.7 101.2 85.8 

2 79.9 108.0 115.2 116.8 115.6 IO5.8 105.9 

3 98,0'^ 126.2* 132.1* 138.4* 

4 102.2 124.9 124.9 114.2 90.2 94.4 108.5 

5 103.6 116.1 118.4 132.1 132.7 129.6 122.1 

6 140.6 177.6 181-2 169.7 168.8 I7I.6 168.3 
Mean 98.0 121.1 124,5 125.2 119.6 120.1 118.1 




65 

the X'lrords per minute ranged from 5^ to 14-1. These values 
were within the first to sixth deciles for oral reading rate 
of 50 college age stutterers on a single trial of a 500-word 
passage (Johnson, 1951). The fastest rate observed, 181 
words per minute for S~5, Trial III, compares; to the ninth 
decile* The mean oral reading rate for suhjects over the 
six trials x-zas 118 words per minute. This rate was between 
the fourth and fifth deciles reported by Johnson (1961). 
It appeared safe to assume the oral reading rates of these 
stuttering subjects v;ere within the normative values pre- 
sented for a similarily designated population. Inspection 
of means by trials suggested that oral reading rate in- 
creased and then decreased as a function of successive 
readings of the same passage. To test the significance 
of this observation, reading rates v;ere rank ordered by trial 
for each subject and submitted to Chi-square analysis. The 
results of this operation indicated the above distribution 
could occur by chance in approximately one out of five 
samples. 

Table 9 lists the percent of disfluent words emitted 
by the stutterers, by subject and trial. The mean percent 
of disfluencies for Trial I, 10,5 3 ^ell between the fifth 
and sixth deciles as reported by Johnson (1961) and the 
range, 1 to 24- per cent, compared to the first to eighth 
deciles also reported by Johnson (1961) for college 



64 



Table 9. Percent of disfluent words for stuttering sub- 
jects. 



Subjects 






Trials 










I 


II 


III 


IV 


V 


VI 


Mean 


, 1 


25.83 


16.41 


12.79 


8.98 


8.79 


7.42 


15.04 


2 


12.21 


6.05 


5.57 


5.08 


5.08 


5.91 


6.28 


5 


14.16* 


4.59* 


3.52* 


2.15* 








4 


5.^7 


4.59 


4.59 


5.47 


7.52 


7.71 


5.86 


5 


8.87 


5.57 


4.59 


5.52 


5.42 


2.64 


4.67 


6 


1.02 


0.65 


0.85 


0.88 


0.54 


0.95 


0.81 


Mean 


10.28 


6.57 


5.59 


4.75 


5.07 


4.52 


6.13 



Not used in computing means. 



65 

stutterers. It appeared that the disflueiicy rates exhibited 
by these subjects were within the range of the reported 
college attending disfluent populations. Examination of the 
means listed for the six trials suggested a decrease in 
disfluency as a function of trials. Inspection of the body 
of Table 9 indicated similar trends for S' s 1, 2, $, and 5. 
Subject ^'s disfluency rate appeared to increase with 
repeated trials and S-5 did not appear to exhibit either 
trend. Chi-sguare analysis indicated no statistical state- 
ments v;ere warranted (probability .20). While this observa- 
tion appeared to be contrary to the frequently reported 
adaptation phenomenon in the stuttering literature (Johnson, 
1937)? the position taken here is that the observation is 
consistent with the data. Further, differences in con- 
clusions may be a result of the analysis procedure. Usual 
data processing involves reduction of measurements to mean 
and variance estimates. Using these procedures, the 
possibility exists that some members of the group will not 
follow the mean. Prior observation of these reversals in 
adaptation effect prompted the use of a statistical tech- 
nique sensitive to heterogeneity within a group. Objective 
defense of this position was offered by Newman (1963) v/ho 
reported six of tv/enty stutterers failed to exhibit de- 
crement of disfluency with successive readings of the same 
passage. 



65 

Analysis comparing the relationship between oral 
reading rate (Table 8) and disfluency frequency (Table 9) 
suggested results similar to those Sander (1961) reported. 
He reported a correlation of .86 between oral reading rate 
and disfluency frequency. Subject 1 had the slowest reading 
rate, 6^ words per minute and the highest disfluency rate, 
2^ per cent. Subjects 2, 3, i;-, and 5 were distributed be- 
tv/een these extremes with tvio reversals, A statistical 
statement on this point was not feasible because of the 
limited sample size. 

Figure 1 presents the cumulative plot of the 
durational distributions of silence intervals for normal 
subjects v/hich occurred during the oral reading of a 1024 
word factual passage. Data are collectively presented for 
the five fluent subjects on the six trials. The data 
points for the trials which represent the upper and lower 
limits are connected by solid lines. Trials within these 
limits are not connected. Cumulative plotting was neces- 
sary because zhe analysis apparatus did not permit equal 
class intervals^ The upper limit of each class interval 
was represented, hence the first data point represents 
frequency of silence intervals between 56 and 90 milliseconds, 
the second between 91-120 milliseconds, to 1050 milli- 
seconds and beyond for the last data point. The curves for 
cumulative durational distributions for silence intervals of 



67 



1300 



o 



1200 



5 liOOl 

o 

!| lOOol 



3 



O 

d 

«3 



900 



7C0 



600 



&00 



5 



400 



300 



£00 



100 1 




100 



200 



300 400 500 600 700 

TirvjE 5f^ JsJl ILL IS ECO S^JDS 



300 



tOOO 



Figure 1. A composite plot of tlie cumulative frequency 
of sxlence intervals for five fluent subjects reading a 102^ 
word passage six times. Solid lines connect the data points 
for tiie upper and lower limits. The individual data points 
falling "between these limits are not connected. 



68 

subjects vj-ith the fastest oral reading rate were approxi- 
mately the shape of an inverted L. As oral reading rate 
decreased, the inflection point was approached more gradu- 
ally, with the curves of the slower reading subjects 
exhibiting a greater absolute frequency of silence intervals 
at all durations., 

Miniiie (1955) investigated the effects of instruc- 
tions on durational distributions for silence intervals. A 
group of twelve graduate students were instructed to read 
a 300-word passage in their (1) normal manner, (2) at a 
much faster rate, and (3) at a much slower rate. Timing of 
oral reading rate confirmed that the instructions produced 
significant differences in total reading time. Findings 
noted above relative to the point of inflection of the 
cumulative curve of durational distributions of silence 
intervals and systematic shifts in absolute frequency were 
observed. Minif ie ' s research also pointed out the sensi- 
tivity of the d'orational distribution of speech and silence 
intervals to instructional variables. In the current 
investigation, where the instructions remained constant, 
cumulative curves of distribution of silence intervals for 
fluent subjects did not shift to an extent sufficient to 
warrant comment. 

The data for durational distributions for disfluent 
(stuttering) speakers were plotted for each subject 



69 

individually, comparing each subject to himself on several 
trials and to the composite durational distributions for 
normal speakers. 

Figure 2 presents the cumulative durational distri- 
bution plot of stuttering S~l for Trials I, III, and V. 
The three trials have fevrer silence intervals at the 90 and 
150 millisecond class intervals than the normal group. At 
time intervals above these values the curve accelerates at 
an increasing and then decreasing rate relative to the 
normal group. Beyond I50 milliseconds, the curves for 
Trials III and V appear to approximate more closely those 
of the normal subjects. 

Figure 5 presents the cumulative durational distri- 
butions of Trials I, III., and V for stuttering S-2. As in 
Figure 2^ the frequency of silence intervals below 90 
through 150 milliseconds is less than that observed for the 
normal subjects, although not to as great an extent as S-1. 
Above these time values, the curves accelerate at a decreas- 
ing rate compared to the curves for the normal subjects. 
Trial 1 5 v/hich exhibited a disfluency rate of 12 per cent 
and an oral reading rate of 80 words per minute, is the 
least similar to the curves for normal subjects, with the 
greatest differences occurring above 5OO milliseconds. 
Trials III and V which were similar in percentage of dis- 
fluencies and oral reading rates, 5.'^ and 5.1 per cent 



70 



BCO 






gioco 

o 

a 

■Ci. 



^700 






0^ 

&5C0 I 



S400 



300 ■ 






uiGO 



Percent of 
Disfluent Words 



Trial 

I 23.8 

m 12.8 

z as 




iCO 2C0 3C0 m SCO 600 7K) 
TIME IN MILLISECONDS 



SCO 500 ICCO 



Figure 2. The cumulative frequency of silence events 
for Subject 1 in Trials I, III, and V, 



71 



BOO 



1230 

S3 r 
snoot 



o 

I 



1"? 



o 



S3 

U1C3 i 



it 



Percent of 
Disf luent Words 



Tria 

I 12.2 

IE 5.4 

Z 5.1 



S-2 




iCO 2C0 SCO 4G0 5CX) 6C0 7Cffl 800 900 1C50 
TIME IN MILLISECONDS 



Figure 3. Tlie cumulative frequency of- silence events 
for Subject 2 on Trials I, III, and V. 



72 

disfluencies and oral reading rates of 115-2 and 113.6 
words pel" minute, exhibited similar curves of cumulative 
durational distributions for silence intervals. 

The curves for the cumulative durational distribu- 
tion of silence intervals for S-3 are presented in figure ^, 
Trial V is not presented because the noise level on the 
tapes for Trials V and VI was inordinately high. The pre- 
ceding statements concerning the comparatively fewer silence 
intervals below 150 milliseconds are also observed here. 
The curve for Trial I shows an increase in silence intervals 
above 600 milliseconds. This increase occurred with S-2 on 
Trial I in the range of 500 milliseconds. 

The curves in Figure 5 represent the cumulative 
durational distributions for stuttering S-^- on Trials I, 
III, and V. The curves for these trials exhibit topo- 
graphical properties similar to the previously presented 
stutterers. Relative to the normal subjects, they show an 
increasing and then decreasing rate of acceleration, with 
acceleration again increasing slightly in the 500 milli- 
second range. Also, for the class intervals ending with 90 
through 150 milliseconds, there were fewer silence intervals. 
It is of further interest to note that this subject did not 
show a progressive decrement in disfluencies with successive 
readings of the material. Reading rate increased and then 
decreased (Trial I, 102 wpm, Trial III, 125 wpm, Trial V, 



73 



i 

1300 1. 
1200 



o 



|liJ03| 
o 

Q 

fa 
170) 



UJ 

o 

1 623 

to 

>- 

> 
§200 

Is 



Tria 

I 

rrr — 



Percent of 
Disfluent Words 



14.2 
3.3 



S-3 




ICO 2Ca 3C0 4C0 500 600 700 
TIME IN MILLISECONDS 



800 9G0 IKJO 



Figure ^. Tne cumulative xrequency of silence events 
for. Subject 3 on Trials I, HI? and. V, 



7^ 



DCO 



^1200 

a 
SllCO 



o 

a 

i3 803 



:7Ca 



o 



^5G0 

>- 



32C0 



OIK) 



Percent of 
Trial Disfluent Words 

T 



S-4 



m- 
2: - 



5.5 
4.6 
7.5 




ICO 2(X) 300 4C0 500 600 700 800 900 
TIME IN MILLISECONDS 



ICCO 



Figure 5. The cumulative frequency of silence events 
for Subject A- on Trials I, III, and V, 



75 

90 wpm). Disfluency percentage decreased and tlien increased 
(Trial I, 5.5 per cent, Trial III, ^.6 per cent. Trial V, 
7.5 per cent). These cumulative durational distributions 
of silence intervals reflected these changes in as much, as 
Trials I and V were more similar to each other than to 
Trial III, which had the fewest disfluencies and fastest 
oral reading rate. 

The cumulative durational distributions of silence 
intervals for stuttering S-5 are presented in Figure 6. At 
the 90 through 150 milliseconds class intervals, the dif- 
ferences between the cumulative durational distribution 
curves for this subject, as compared to the composite curve 
for the normal subjects, are small. Trial I which was 
judged to have 9 per cent disfluencies, exhibited topo- 
graphical properties similar to those of the previously pre- 
sented stutterers. Trials III and V, where disfluency 
percentages were small (4- and 3 per cent), fell within the 
boundaries for the normal subjects. 

Figure 7 presents the cumulative durational distri- 
butions of silence intervals for stuttering S-6 on Trials 
I, III, and V. This subject's curves were of particular 
interest because he was considered to be a stutterer both 
by himself and by several Speech Pathologists, Yet, during 
these trials his disfluency and oral reading rates were 
within the range for normal subjects. The differences below 



76 



1300 



„1200! 
1 1100 



o 

o 



O 

gsco 

i 



v> 

o 

S400 
Cr 

§200 . 



Trial 

I a 9 

m-^ 44 
I 3.4 



Percent of 
Disfluent Words 



S-5 




100 200 300 400 300 600 700 800 900 1000 
\ . - . . TIME IN MILLISECONDS _„ _ 

Figure 6, Ttie cumulative frequency of silence events 
for Subject 5 on Trials I, III, and V. 



77 



DOO 



o 



12G0 



S 1100 1 

|lKiO 

o 

IT ^ 
O 

B 

i700 



1 600 
Ml 

§400 
^300 
§200 
"ICO 



Percent of 
Trial Disfluent Words 

I 1.0 

HI 0.8 

X- — as 



S-6 




m 200 300 400 500 600 700 
TIME IN MILLISECONDS 



900 1000 



Figure 7. The cumulative frequency of silence events 
for Subject 6 on Trials I, III, and V, 



78 

150 milliseconds were not remarkable wlien comparing this 
subject to the normal subjects. The general topographical 
properties for Trials I, III, and 7 of this subject more 
closely approximated the durational distributions of silence 
intervals for the normal subjects than for the stuttering 
subjects previously reported. 

To varying degrees, the durational distributions of 
silence intervals for stutterers appeared to differ quanti- 
tatively from the composite data for normal speakers on the 
first several class intervals, 90 through 150 milliseconds. 
The stutterers had fewer silence intervals at these dura- 
tions than did the normal speakers. There appeared to be 
a tendency for the curves associated with the highest dis- 
fluency percentages and slowest oral reading rates to be 
moat dissimilar from the composite curves for the normal 
subjects. These curves showed a tendency to increase and 
then decrease in acceleration as compared to the curves 
for the normal subjects. As the disfluency percentages and 
oral reading rates of the stutterers more closely approxi- 
mated those of the normal subjects, the curves for the 
cumulative durational distribution of silence intervals 
more nearly approximated those of the normal subjects. The 
cumulative durational distribution curves for a stuttering 
subject whose oral reading and disfluency rates were within 
normal range were essentially within the range of the normal 
subject's cumulative durational distributions. 



79 

The observations herein reported seem to warrant 
further research of speech and silence durational distri- 
butions as potential areas which may lead to objective 
procedures for measuring the type and extent of the dis- 
fluency phenomenon. 



APPENDIX B 
SUPPLEMENTARY STATISTICAL SUMMARIES 

Table 10 presents the reliability coefficients for 
the Multiple -01 ass Time Analyzer. Table 11 presents the 
reliability coefficients for the reading time and dis- 
fluency measurement procedures. 

Tables 12 through 15 present the smomaries of the 
analyses of variance for experimenter-subject combinations 
by time of day variables for reading times on Trials I and 
II and for disfluencies occurring during Trials I and II. 

Tables 16 through 2? present the summaries of the 
significant analyses of variance for experimenter-subject 
combinations by time of day variables. Tables 16 through 
22 present these summaries for speech and silence events 
occurring during Trial I. Tables 23 through 27 present 
these summaries for speech and silence events occurring 
during Trial II. 



80 



81 



Table 10. Reliability coefficients of the Multiple-Class 
Time Analyzer for speech, and silence events. 



Time (milli- 
seconds) 
CI 


Speech 


Silence 


50- 99 


.978 


.995 


100-1^9 


.969 


.992 


150-199 


.955 


.986 


200-2*4-9 


.944 


.957 


250-299 


.948 


.976 


500-5^9 


.950 


.932 


350-399 


.947 


.970 


400-^*4-9 


.970 


.938 


450-499 


.971 


.844 


500-549 • 


.917 


.930 


550-599 


.934 


.939 


600-649 


.951 


.917 


650-699 


.960 


.961 


700-749 


.963 


.943 


750-Z 


.992 


.988 



Table 11. Reliability of reading time and disfluency 
measurement procedures. 



Measure Correlation 

Between Within 



Heading time in seconds .985 ,999 

Disfluency frequency .97^ .791 



82 



83 



TalDle 12. Summary of analysis of variance for escperimenter- 
subject combinations by time of day variables for reading 
time of Trial I. 



Source d.f. SS ms F 



E S Comb. 


3 




46.11 


15.37 


Time of Day 


3 




200.27 


66.77 


Interaction 


9 




511.22 


55.80 


Vitbin 


48 


4 


,457.62 


92.87 



Table 15. Summary of analysis of variance for experimenter- 
subject combinations by time of day variables for reading 
time of Trial II. 



Source 


d.f. 


SS 


ms 


F 


E S Comb. 


3 


23.94 


7.98 


- 


Time of Day 


3 


177.64 


59.21 


-. 


Interaction 


9 


381-95 


42.44 


mm 


Within 


4-8 


3,427.90 


71.41 





8-4- 



Table m-. Summary of analysis of variance for experimenter- 
subject combinations by time of day variables for dis- 
fluencies occurring during Trial I. 



Source 



E S Comb. 
Time of Day 
Interaction 

VitMn 



d.f. 



5 

3 

9 

^8 



SS 



ms 



1.19 0.^0 

9.62 3.21 

106.58 11.82 

28^.25 5.92 



F 



2.00 



Table 15. Summary of analysis of variance for experimenter- 
subject combinations by time of day variables for dis- 
fluencies occurring during Trial II. 



Source 


d.f. 


SS 


ms 


I 


B S Comb. 


3 


6.05 


2.02 


mm 


Time of Day 


5 


18.17 


6.06 


1.21 


Interaction 


9 


83.27 


9.25 


1.85 


Within 


48 


239.75 


^^-.99 





85 



Table 15. Summary of analysis of variance for experimenter- 
subject combinations by time of day variables for 
frequency of silence events between 100-1^1-9 milliseconds 

on Trial I. 



Source d.f. SS 



ms 



E S Comb. 


3 


Time of Day 


3 


Interaction 


9 


Within 


^8 



3,032.69 1,010.90 3.83" 

338.9^ 112.98 

2,773.18 308.13 

12,652.17 263.59 



*F .05 (d.f. = 5A0) = 2.84 



Table 17, Summary of analysis of variance for experimenter- 
sub;ject combinations by time of day variables for 
frequency of speech events between 150-199 milliseconds 

on Trial I. 



Source d.f. SS ms F 



E S Comb. 5 365.90 121.96 

Time of Day 3 122.90 40.96 

Interaction 9 622.29 2.94-" 

Within 48 1,124.92 23.45 



E .05 (d.f. = 8/40) = 2.18 



86 



Table 18. Summary of analysis of variance for experimenter- 
subject combinations by time of day variables for 
frequency of speech events between ^00-^99 milliseconds 

on Trial I. 



Source d.f, SS ms F 

E S Comb. 3 l?.*^-^ 5.81 

Time of Day 5 156.0? 52.02 ^.01* 

Interaction 9 37.81 -4-. 20 

Within ^8 609.17 12,69 

*F .05 (d.f. = 3A0) = 2.8^ 



Table 19. Summary of analysis of variance for experimenter- 
subject combinations by time of day variables for 
frequency of silence events between 4-50-A-99 milliseconds 

on Trial I. 

Source d.f. SS ms F 



E S Comb, 




5 ■ 




19.69 


6.56 


Time of Day 




3 




8.^A- 


2.81 


Interaction 




9 




72.81 


8.09 


Within 




1^8 




157.17 


3.27 


*F .05 (d. 


f. 


= 8A0) 


= 2 


.18 





2.^7' 



87 



Table 20, Summary of analysis of variance for experimenter- 
subject combinations by time of day variables for 
frequency of silence events between 500-5^9 milliseconds 

on Trial I, 



Source 


d.f. 


SS 


ms 


F 


E S Comb. 


3 


5.07 


1.69 


. 


Time of Day 


5 


28.57 


9.52 


3.17* 


Interaction 


9 


50.06 


3.34 


- 


Within 


48 


136.17 


2.84 





*F .05 (d.f. = 3/40) = 2.84 



Table 21. Summary of analysis of variance for experimenter- 
subject combinations by time of day variables for tlie 
frequency of silence events between 600-549 milliseconds 

on Trial I. 

Source d.f, SS ms F 

3.07* 



E S Comb. 




5 . 




29.21 


9.74 


Time of Day 




5 




8.21 


2.74 


Interaction 




9 




21.60 


2.40 


VittLin 




48 




152.42 


3.18 


*F .05 (d. 


f. 


= 3/40) 


= 2 


.84 





88 



Table 22. Summary of analysis of variance for experimenter- 
subject combinations by time of day variables for 
frequency of speecli events between 550-699 milliseconds 

on Trial I. 

Source d.f. SS ms F 



2.87' 



E S Comb. 


3 


5.53 


1.11 


Time of Day 


3 


15.53 


^.■4-^ 


Interaction 


9 


12.85 


1.^3 


Within 


^8 


7^. ^2 


1.55 



P .05 (d.f. = 3A0) = 2.84 



Table 25. Summary of analysis of variance for experimenter- 
subject combinations by time of day variables for 
frequency of speech, events between 250-299 milliseconds 
on Trial II. 

Source d.f. SS ms F 



2.92' 



E S Comb. 


5 


25.57 


8.52 


Time of Day 


3 


15^.57 


51.52 


Interaction 


9 


558.44 


19.81 


Within 


H-8 


847.17 


17.65 



*F .05 (d.f. = 5/40) = 2.84 



89 



Table 2A-. Summary of analysis of variance for experimenter- 
subject combinations by time of day variables for 
frequency of speecli events between 550-399 milliseconds 

on Trial II, 



Source d.f. SS ms F 



E S Comb. 5 17^.9^ 58.51 5.59^ 

Time of Day 5 66.57 22.19 

Interaction 9 128.06 1^.23 

Vitbin ^8 82^.67 17.18 



*F .05 (d.f. = 5A0) = 2.8^ 



Table 25. Summary of analysis of variance for experimenter- 
subject combinations by time of day variables for 
frequency of silence events between 650-699 milliseconds 

on Trial II. 



Source 


d.f. 


SS 


ms 


F 


E S Comb. 


5 


1.19 


.^0 


_. 


Time of Day 


5 


17.69 


5.90 


3.23* 


Interaction 


9 


25.93 


2.66 


- 


Within 


^8 


87.67 


1.85 





*F .05 (d.f. = 3A0) = 2.84 



90 



Table 26, Summary of analysis of variance for experimenter- 
subject combinations by time of day variables for 
frequency of speech events between 700-7^9 milliseconds 
on Trial II. 



Source 


d.f 


SS 


ms 


F 


E S Comb. 


3 


0.82 


0.27 


- 


Time of Day 


3 


2.07 


0.69 


- 


Interaction 


9 


15.93 


1.77 


2.52* 


Within 


48 


33.67 


0.70 





F .05 (d.f. = 8A0) = 2.18 



Table 27. Summary of analysis of variance for experimenter- 
subject combinations by time of day variables for 
frequency of silence events beyond 750 milliseconds 
on Trial II. 

Source d.f. SS ms F 

62.06 3.^7* 
30.90 

5.89 
17.88 
*P ,05 (d.f. = 3A0) = 2.84 



E S Comb. 


3 


186.19 


Time of Day 


3 


92.69 


Interaction 


9 


53.06 


Within 


48 


858.17 



APPENDIX G 
Z SCOHE DATA FOR THE INDIVIDUAL STUTTERING SPEAKERS 

Figures 8 througli 19 graphically present tlie 
individual Z scores for the significant speech and silence 
class intervals of the stuttering speakers. 



91 



SPEECH 
EVENTS 
50- 99 

100-19^ 

150-199 

200-2^9 

250-299 

350-399 
CO 

§ SILENCE 
g EVENTS 



50- 99 



[^ 

CO 
M 

^ 100-1^9 

1^ 150-199 

CO 200-2^9 

> 250-299 

g 300-3^9 

H 

CO ^00-^^9 

CO 

I 500-5^9 
550-599 



600-649 

750- X 




2 3^56 
Z Score Units 



7 8 9 10 11 12 



Reading time (sec.) 
Disfluency percentage 



Total disfluencies 



89.0 
1.7 



Interjections 

Part word repetitions 

Word repetitions 

Prolongations 

Revisions 



1 
1 
1 
1 
1 



Figure 8. Z scores at significant speech and 
Silence class intervals for male stutterer, age 22. 



SPEECH 
EVENTS 
50- 99 

100-149 

150-199 

200-2^9 

250-299 

350-399 

§ SILENCE 
8 EVENTS 

^ 50- 99 

n 100-1^9 
g 150-199 

^ 200-2^9 
fe 250-299 
I 300-549 

H 

W ^00-449 

CO 

I 500-549 
550-599 

600-649 

750- X 




9 10 11 12 



Z Score Units 



Reading time (sec.) 95.0 
Disfluency percentage 3-7 



Total disfluencies 



11 



Interjections 1 
Part word repetitions 4 
Word repetitions 1 
Prolongations 4 
Revisions 1 



Figure 9. Z scores at significant speech, and 
silence class intervals for female stutterer^ age 18. 



g 
O 

o 

m 

H 

\A 
H 

s 

H 
03 



EH 

H 

CQ 
CO 

hi 
O 



SPEECH 
EVENTS 
50- 99 

100-149 

150-199 
200-2^9 

250-299 

350-399 

SILENCE 
EVENTS 

50- 99 
100-1^9 

150-199 
200-2^9 

250-299 
300-349 
400-449 
500-549 
550-599 

600-649 

750- X 




-2-101 2 3 ^5 6 7 8 9 10 11 12 
Z Score Units 



Heading time (sec.) 110.0 
Disfluency percentage I.3 

Total disfluencies ti- 



Interjections l 
Part word repetitions 1 
Word repetitions 1 
Prolongations l 
Revisions q 



Figure 10. Z scores at significant sneecii and 
sxlence class intervals for male stutterer, age 23. 



SPEECH 
EVENTS 
50- 99 

100-1^9 

150-199 

200-2^1-9 

g 250-29<^ 
o 

w 550-59S 

^ SILENGI 
M EVENTS 

a 50- 9^ 

CO 100-1 ^S 

> 200-2^S 

I 250-29S 

^ 300-5^S 

3 400-4^9 
o 

500-5^9 
55O-59C 

600-6^9 

750- X 




12 3^56 
Z Score Units 



9 10 11 12 



Seading time (sec.) 110.5 
Disfluency percentage 2.0 



Total disfluencies 



Interjections 
Part word repetitions 1 
Word repetitions 2 
Prolongations 4 
Revisions 



Figure 11. Z scores at significant speech and 
silence class intervals for female stutterer, age 18. 



SPEECH 
EVENTS 
50- 99 

100-1^9 

150-199 
200-249 

250-299 

I 350-399 

8 SILENCE 
g EVENTS 

^ 50- 99 

M 

^ 100-1^^9 



95 



w 



150-199 



^ 200-2^9 
g 250-299 
•"^ 300-349 

«^ ZfOO-449 

O 

500-549 

550-599 

600-649 

750- X 



-2 -1 



-1- ^ ; 4 j. ^ ') M i^ ii i'2 



Z Score Units 



Reading time (sec.) 110. 5 
Disfluency percentage 2.0 



Total disfluencies 



Interjections 
Part word repetition.s 1 
Word repetitions 1 
Prolongations 2 
Revisions 5 



Figure 12. Z scores at significant speech, and 
silence class intervals for male stutterer, age 22. 



SPEECH 
BVE^'TS 
50- 99 

100-1^9 

150-199 

200-2^9 

250-299 
350-599 




-2 -1 



0123^56789 10 11 12 
Z Score Units 



Reading time (sec.) 125.0 
Disfluency percentage ' 4.7 



Total disfluencies 



14 



Interjections 5 

Part word repetitions 3 

Word repetitions 1 

Prolongations 5 

Revisions 



Figure I5. Z scores for significant speech and 
silence class intervals for male stutterer, age 20, 



SPEECH 



98 



EVENTS 




1 




50- 99 




_ 




100-1^9 
150-199 
200-2^9 
250-299 
1 350-399 




































SILENCE 




1 


W EVENTS 




i 


^ 50- 99 










^ 100-1^9 




.__ 




iz; 








*^ 150-199 










■^ 200-249 








^ 250-299 




^ £-^V-/ (^ J J 








^ 500-349 
02 










^ 400-449 

500-549 
550-599 
















— 




600-649 




■ 




750- X 








1 ' 


1 t 1 i 1 i 1 1 I 1 1 1 





-2 -1 



12 3^56 
Z Score Units 



7 8 9 10 11 12 



Reading time (sec.) 196.0 
Disfluency percentage 11.5 



Total disfluencies 5^ 



Interjections 4 
Part word repetitions 9 
Word repetitions 10 
Prolongations 9 
Revisions 2 



Figure 14. Z scores for significant speech and 
silence class intervals for male stutterer, age 28, 



(=1 

o 
o 

CO 
H 

t^ 

H 



EH 

12; 

H 
CO 

CO 



50- 99 
100-1^9 
150-199 
200-2^9 
250-299 
350-599 

SILENCE 
EVENTS 

50- 99 
100-1^9 
150-199 

200-249 
250-299 
500-349 
400-449 
500-549 
550-599 
600-649 

750- X 



<r 



3.5 



99 



_l L 



-2-1 1 



2 5^5 6 7 8 9 10 11 12 
Z Score Units 



Reading time (sec.) 199.5 
Disfluency percentage 12.3 



Total disfluencies 



54 



Interjections 6 
Part word repetitions 4 
Word repetitions 9 
Prolongations I5 
Revisions 2 



Figure I5. Z scores for significant speech and 
silence class intervals for male stutterer, age 19. 



SPEECH 
EVENTS 
50- 99 

100-1^9 

150-199 

200-2^9 

250-299 

g 550-599 
o 

H SILENCE 
^ EVENTS 

1:^ 50- 99 
^ 100-1^9 

H 

03 150-199 

> 200-2^9 
g 250-299 

H 

w $00-5^9 

3 ^00-^^9 
o 

500-5^9 
550-599 

600-6^9 

750- X 



100 



_J L 



18.4 



J 1 i I < ' ' ' I I I L 



-2-10 1 254567 8 9 10 11 12 
Z Score Units 



Reading time (sec.) 240.0 
Disfluency percentage -24.7 



Total disfluencies 



74 



Interjections 7 

Part word repetitions 29 
Word repetitions 8 
Prolongations 30 
Revisions 



5'igure 15. Z scores for significant speech and 
silence class intervals for male stutterer, age 29. 



SPEECH 
EVENTS 

50- 99 
100-1^9 
150-199 
200-2^9 
250-299 

CO 

g 550-599 

o 

§ SILENCE 
^ EVENTS 

t^ 50- 99 
^ 100-1^9 

^ 150-199 

^ 200-2^9 
^ 250-299 

CO 300-5^9 

CO 

< i^.00-^^9 

G 

500-5^9 
550-599 
600-6^9 

750- X 



101 



-2-1-0 1 2 5 ^5 6 7 8 9 10 11 12 
Z Score Units 



Heading time (sec.) 407.5 
Disfluency percentage 21.0 



Total disfluencies 69 



Interjections 

Part word repetitions 

Word repetitions 

Pr ol ongations 

Revisions 



12 
1 

16 
5 
5 



Figure 17. Z scores for significant speecli and 
silence class intervals for male stutterer, age 21, 



SPEECH 
EVEITTS 

' 50- 99 
100-1^9 
150-199 
200-2A-9 

250-299 

1 550-599 

o SILENCE 
S EVENTS 

l^ 50- 99 
^ 100-1^9 

J^ 150-199 

^ 200-2^9 

i^ 250-299 

^ 500-3^9 

2 A-00-^^9 
o 

500-5^9 
550-599 
600-6^9 

750- X 



102 



20.7 



-2-1 1 



-i — I 1 1 1 1 1 1 1 I i__ 

25 Z 5 6 78 9 10 11 12 

Z Score Units 



Reading time (sec.) ^09.0 
Disfluency percentage 59.0 



Total disfluencies 117 



Interjections 55 

Part word repetitions 5^ 

Word repetitions 9 

Prolongations 19 

Revisions 2 



Figure 18. Z scores for significant speech and 
silence class intervals for male stutterer, age 27. 



SPEECH 
EVENTS 

50- 99 
100-1^9 
150-199 
200-2^9 
250-299 
1 550-399 

§ SILENCE 
w EVENTS 

M 

t^ 50- 99 

^ 100-1^9 

02 150-199 
^ 200-249 

I 250-299 

^ 300-549 
CO 

^ ii.00-449 

o 

500-5^9 
550-599 

600-649 

750- X 



105 



40.3 



-2-1 1 2 5 45 6 7 8 9 10 11 12 
Z Score Units 



Reading time (sec.) 659.0 
Disfluency percentage 45.7 



Total disfluencies 157 



Interjections 

Part word repetitions 120 
Word repetitions 2 
Prolongations 15 

Revisions 



Eigure 19. Z scores at significant speech, and 
silence class intervals for male stutterer, age 21. 



EEFERENCSS 



Adams, L, A comparison of certain sound wave cliaracteristics 
of stutterers and non-stutterers. Chapter 58 in V. 
Johnson (ed.)» Stuttering in Children and Adults . 
Minneapolis : Univ. Minn. Press (1955). 

Berelson, B. , and Steiner, C. Human Behavior , New York: 
Harcpurt, Brace and World, Inc., 297-50^ (1964-). 

Black, J. Natural frequency, duration, and intensity of 

vowels in reading. J. Speech Hearing Pis ., 1^, 216-221 
(19^9). 

Bloodstein, 0. Studies in the psychology of stuttering: XIX. 
The relationship "between oral reading rate and severity 
of stuttering. J. Speech Pis ., 9, 161-175 (19^^). 

Bryngelson, B. A photophonographic analysis of the vocal 
disturbances in stuttering. Psychol, Monogr . , 4-5, 1-50 
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Carroll, J. Language and Thought . Englewood Cliffs, New 
Jersey: Prentice-Hall, Inc., 72 (196^). 

Cullinan, W. , Prather, E. and Villiams, D. Comparison of 

procedures for scaling severity of stuttering. J. Speech 
Hearing Res ., 6, 187-19^ (1965). 

Parley, F. A normative study of oral reading rate. Master's 
thesis, Univ. of Iowa (19^0). 

Fairbanks, G. Voice and Articulation Prillbook . New York: 
Harper (19^^07"^ 

Flanagan, B. , Goldiamond, I., and Azrin, N. , Operant Stut- 
tering: The control of stuttering through response con- 
tingent consequences. J. Exp. Anal. Behavior , 175-176 
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. Instatement 

of stuttering in normally fluent individuals through 
operant procedures. Science, 150, 979-981 (1959). 

10^ 



105 

G-iDbons, B, , Winchester, R. , and Krebs, D. The variability 
of oral reading rate. J. S peech. Hearing Dis., 23, 591- 
595 (1958). 

Goldiamond, I. Indicators of perception I, Subliminal per- 
ception, subception, unconscious perception: an analysis 
in terms of psychophysical indicator methodology. 
Psychol. Bull ., 55, 573-^11 (1958). 

. Stuttering and fluency as a manipulatable 

operant response class. Chapter 6 in L, Krasner and L, 
Ullman (eds.) Research in Behavior Modification . New 
York: Holt, Rinehart and Winston, Inc. (.1965). 

Hargreaves, V/. and Starkweather, J, Collection of temporal 
data with the duration tabulator, J. of Exp. Anal. 
Behavior , 2, 179-183 (1959). ' 

Hargreaves, V/. A model for speech unit duration. Language 
and Speech , 3, 16^-173 (I960), 

Hill, H. Stuttering: I. A critical review and-^ evaluation of 
biochemical investigations, J. Speech Dis,, 9, 24-5-261 
(19^4a). 

Stuttering: II. A review and integration of physio- 



logic data. J. Speech Dis . , 9j 289-32^ (19^^b). 

House* A. On vowel duration in English, J, Acoust. Soc, Amer , , 
33, 117^-1178 (1961). 

Johnson, W. Measurements of oral reading and speaking rate 
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non-stutterers. J. Speech Hearing Dis ., Monograph Suppl., 
7, 1-20 (1961). 

Johnson, W. and Knott, J. Studies in the psychology of 

stuttering: I. The distribution of moments of stuttering 
in successive readings of the same material, J. Speech 
Dis., 2, 23-25 (1957). 

Leach, E, Personal communication. (1965), 

Lewis, D.,,and Sherman, D. Measuring the severity of stut- 
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McNemar.^ Q. Psychological Statistics , second edition, Kew 
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Milisen, R. Methods of evaluation and diagnosis of speech dis- 
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TXWTTr 



106 

Minifie, ^. An analysis of tlie durational aspects of con- 
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Minifie, F. and Cooker, H. A disfluency index,. J. Speech. 
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Newman, P. Adaptation performances of individual stutterers: 
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Pavlov, I. Conditioned Refle:>ces. ; An Investip^ation of the 

Physiologic Activity of the Cerehral Cortex . Translated 
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Roberts, P. Speech sound time and oral reading time of 

college stutterers and non-stutterers. Speech Monogr . , 
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Roe, A. and Derbyshire, A. Quantifying periods of silence 
and sound in speech. Paper read at 1958 Convention of 
the American Speech and Hearing Association (1958). 

Robinson, P. Effects of changes in the relationship between 
the speech and external side-tone level in the oral 
reading rate of stutterers and non-stutterers. Ph.D. 
dissertation, Ohio State University (1951). 

Sander, E. Reliability of the Iowa Speech Disfluency Test. 

J. Speech Hearing Dis ., Monograph Suppl., 7$ 21-30 (1961). 

Sharf, D. Duration of post-stress intervocalic stops and 

preceding vowels. Language and Speech , 5j 26-30 (1962). 

Sherman, D. and Trotter, V/. Correlation between two measures 
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Siegel, G. and Martin, R. Verbal punishment of disfluencies 
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Staats, A. and Staats, C. Complex Human Behavior . New York: 
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Starbuck, H, and Steer, M. The adaptation effect in stut- 
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107 

steer, M. Tlie general intelligence of college stutterers. 
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Travis, L. Studies in stuttering II: Photographic study of 
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Travis, L. A phonophotographic study of the stutterer's 

voice and speech. Psychol. Monogr . , 56, 109-1^1 (1927q). 

Tuthill, C. A quantitative study of extensional meaning 

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81-98 (19^6). 

Verzeano, M. Time patterns of speech in normal subjects: 

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. Time patterns of speech in normal subjects: 

II. J. Speech Hearing Ms ., 16, 5^5-550 (1951). 

Vendahl, R. and Cole, J. Identification of stuttering 

during relatively fluent speech, J. Speech Hearing Res , , 
^■, 281-286 (1961). 

Vilcoxon, P. Some Rapid Approximate Statistical Procedures . 
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Williams, D. An evaluation of mossetic muscle action po- 
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Williams, D. A point of view about stuttering. J. Speech 
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n^sij: 



BIOGRAPHICAL SKETCH 

Bruce C. Flanagan was born July 31, 1929, at Neenali, 
Wisconsin. From 19^6, until 1948, lie served in the United 
States Army and was stationed in Japan. Following Ms dis- 
charge from the army he completed his high school education 
at Tupelo High School. In August, 1953, he received the 
degree of Bachelor of Science from Western Michigan College 
of Education. From 1953, until 1956, he was employed as a 
speech therapist by the Board of Education of Alpena, 
Michigan. In August, 1958, he received the degree of Master 
of Science from Southern Illinois University. From 1958, 
until I960, he worked as a research assistant in the Per- 
ception and Conditioning Laboratory of Southern Illinois 
University. Since I960 he has held an appointment as 
assistant professor in the Behavioral Science Program at the 
University of South Florida. In September, 1952, he enrolled 
in the Graduate School of the University of Florida. In 
1963, while working toward the degree of Doctor of Philosophy, 
he was a Vocational Rehabilitation grantee. 

Bruce C. Flanagan is married to the former Patricia 
Anne Hickok and is the father of three children. He is a 
member of the American Speech and Hearing Association with 



108 



109 



Clinical Competency in Speech.^ the American Association 
for tlie Advancement of Science, the Florida Speech and 
Hearing Association, and the Tampa Bay Psychological 
Association, 



This dissertation was prepared under the direction 
of the chairman of the candidate's supervisory committee 
and has been approved by all members of that committee. It 
was submitted to the Dean of the College of Arts and Sciences 
and to the Graduate Council, and was approved as partial 
fulfillment of the requirements for the degree of Doctor of 
Philosophy, 



June 21, 1966 




Dean, Colle/g 



fgVLj. 



^gfe of i^tS . 



and Sciences 



Supervisory Committee: 



Chairman 



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Dean, Graduate School 



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